| Oracle® Database Globalization Support Guide 11g Release 2 (11.2) Part Number E10729-02 |
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View PDF |
| Oracle® Database Globalization Support Guide 11g Release 2 (11.2) Part Number E10729-02 |
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|
View PDF |
This chapter introduces the Language and Character Set File Scanner and the Database Character Set Scanner. The character set scanner utilities are tools for detecting and verifying valid and invalid data. The Language and Character Set File Scanner supports text files, while the Database Character Set Scanner scans data inside the database.
This chapter contains these topics:
How to Handle Convertible or Lossy Data in the Data Dictionary
Storage and Performance Considerations in the Database Character Set Scanner
The Language and Character Set File Scanner (LCSSCAN) is a high-performance, statistically based utility for determining the language and character set for unknown file text. It can automatically identify a wide variety of language and character set pairs. With each text, the language and character set detection engine sets up a series of probabilities, each probability corresponding to a language and character set pair. The most statistically probable pair identifies the dominant language and character set.
The purity of the text affects the accuracy of the language and character set detection. The ideal case is literary text of one single language with no spelling or grammatical errors. These types of text may require 100 characters of data or more and can return results with a very high factor of confidence. On the other hand, some technical documents can require longer segments before they are recognized. Documents that contain a mix of languages or character sets or text such as addresses, phone numbers, or programming language code may yield poor results. For example, if a document has both French and German embedded, then the accuracy of guessing either language successfully is statistically reduced. Both plain text and HTML files are accepted. If the format is known, you should set the FORMAT parameter to improve accuracy.
This section includes the following topics:
Start the Language and Character Set File Scanner with the LCSSCAN command. Its syntax is as follows:
LCSSCAN [RESULTS=number] [FORMAT=file_type] [BEGIN=number] [END=number] FILE=file_name
The parameters are described in the rest of this section.
RESULTS
The RESULTS parameter is optional.
| Property | Description |
|---|---|
| Default value | 1 |
| Minimum value | 1 |
| Maximum value | 3 |
| Purpose | The number of language and character set pairs that are returned. They are listed in order of probability. The comparative weight of the first choice cannot be quantified. The recommended value for this parameter is the default value of 1. |
FORMAT
The FORMAT paramater is optional.
| Property | Description |
|---|---|
| Default Value | text |
| Purpose | This parameter identifies the type of file to be scanned. The possible values are html, text, and auto. |
BEGIN
The BEGIN parameter is optional.
| Property | Description |
|---|---|
| Default value | 1 |
| Minimum value | 1 |
| Maximum value | Number of bytes in file |
| Purpose | The byte of the input file where LCSSCAN begins the scanning process. The default value is the first byte of the input file. |
END
The END parameter is optional.
| Property | Description |
|---|---|
| Default value | End of file |
| Minimum value | 3 |
| Maximum value | Number of bytes in file |
| Purpose | The last byte of the input file that LCSSCAN scans. The default value is the last byte of the input file. |
FILE
The FILE parameter is required.
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the name of a text file to be scanned |
Example 12-1 Specifying Only the File Name in the LCSSCAN Command
LCSSCAN FILE=example.txt
In this example, the entire example.txt file is scanned because the BEGIN and END parameters have not been specified. One language and character set pair will be returned because the RESULTS parameter has not been specified.
Example 12-2 Specifying the Format as HTML
LCSSCAN FILE=example.html FORMAT=html
In this example, the entire example.html file is scanned because the BEGIN and END parameters have not been specified. The scan will strip HTML tags before the scan, thus results are more accurate. One language and character set pair will be returned because the RESULTS parameter has not been specified.
Example 12-3 Specifying the RESULTS and BEGIN Parameters for LCSSCAN
LCSSCAN RESULTS=2 BEGIN=50 FILE=example.txt
The scanning process starts at the 50th byte of the file and continues to the end of the file. Two language and character set pairs will be returned.
To obtain a summary of the Language and Character Set File Scanner parameters, enter the following command:
LCSSCAN HELP=y
The resulting output shows a summary of the Language and Character Set Scanner parameters.
The Language and Character Set File Scanner supports several character sets for each language.
When the binary values for a language match two or more encodings that have a subset/superset relationship, the subset character set is returned. For example, if the language is German and all characters are 7-bit, then US7ASCII is returned instead of WE8MSWIN1252, WE8ISO8859P15, or WE8ISO8859P1.
When the character set is determined to be UTF-8, the Oracle character set UTF8 is returned by default unless 4-byte characters (supplementary characters) are detected within the text. If 4-byte characters are detected, then the character set is reported as AL32UTF8.
See Also:
"Language and Character Set Detection Support" for a list of supported languages and character setsThe Database Character Set Scanner assesses the feasibility of migrating an Oracle database to a new database character set. The Database Character Set Scanner checks all character data in the database and tests for the effects and problems of changing the character set encoding. A summary report is generated at the end of the scan that shows the scope of work required to convert the database to a new character set.
Based on the information in the summary report, you can decide on the most appropriate method to migrate the database's character set. The methods are:
Export and Import utilities
CSALTER script
CSALTER script with Export and Import utilities on selected tables
Note:
If the Database Character Set Scanner shows conversion exceptions, then these problems must be fixed before using any of the described methods. This may involve further data analysis and modifying the problem data to eliminate those exceptions. In extreme cases, both the database and the application might need to be modified. Oracle recommends you contact Oracle Consulting Services for services in database character set migration.The Database Character Set Scanner reads the character data and tests for the following conditions on each data cell:
Do character code points of the data cells change when converted to the new character set?
Can the data cells be successfully converted to the new character set?
Will the post-conversion data fit into the current column size?
The Database Character Set Scanner reads and tests for data in CHAR, VARCHAR2, LONG, CLOB, NCHAR, NVARCHAR2, NCLOB and VARRAY columns as well as nested tables. The Database Character Set Scanner does not perform post-conversion column size testing for LONG, CLOB, and NCLOB columns.
The Database Character Set Scanner provides four modes of database scan:
The Database Character Set Scanner reads and verifies the character data of all tables belonging to all users in the database including the data dictionary (such as SYS and SYSTEM users), and it reports on the effects of the simulated migration to the new database character set. It scans all schema objects including stored packages, procedures and functions, and object definitions stored as part of the data dictionary.
To understand the feasibility of migrating your database to a new database character set, you need to perform a full database scan.
The Database Character Set Scanner reads and verifies character data of all tables belonging to the specified user and reports on the effects on the tables of changing the character set.
The Database Character Set Scanner reads and verifies the character data of the specified tables, and reports the effects on the tables of changing the character set.
The Database Character Set Scanner reads and verifies the character data of the specified columns, and reports the effects on the tables of changing the character set.
This section describes how to install and start the Database Character Set Scanner. It includes the following topics:
To use the Database Character Set Scanner, you must have DBA privileges for Oracle Database.
Before using the Database Character Set Scanner, you must run the csminst.sql script to set up the necessary system tables on the database that you plan to scan. The csminst.sql script needs to be run only once. The script performs the following tasks to prepare the database for scanning:
Assigns the necessary privileges to CSMIG
Assigns the default tablespace to CSMIG
Creates the Character Set Scanner system tables under CSMIG
You can modify the default tablespace for CSMIG by editing the csminst.sql script. Modify the following statement in csminst.sql to assign the preferred tablespace to CSMIG as follows:
ALTER USER csmig DEFAULT TABLESPACE tablespace_name;
Ensure that there is sufficient storage space available in the assigned tablespace before scanning the database. The amount of space required depends on the type of scan and the nature of the data in the database.
On UNIX platforms, run csminst.sql using these commands and SQL statement:
% cd $ORACLE_HOME/rdbms/admin
% sqlplus sys/password as sysdba
SQL> START csminst.sql
You can start the Database Character Set Scanner from the command line by one of these methods:
Using the Database Character Set Scanner parameter file
CSSCAN username/password PARFILE=file_name
Using the command line to specify parameter values. For example:
CSSCAN username/password FULL=y TOCHAR=al32utf8 ARRAY=10240 PROCESS=3
Using an interactive session
CSSCAN username/password
In an interactive session, the Database Character Set Scanner prompts you for the values of the following parameters:
FULL/TABLE/USER
TOCHAR
ARRAY
PROCESS
If you want to specify other parameters, then use the Database Character Set Parameter file or specify the parameter values in the CSSCAN command.
The Database Character Set Scanner parameter file enables you to specify Database Character Set Scanner parameters in a file where they can be easily modified or reused. Create a parameter file using a text editor.
Use one of the following formats to specify parameters in the Database Character Set Scanner parameter file:
parameter_name=value parameter_name=(value1, value2, ...)
You can add comments to the parameter file by preceding them with the pound sign (#). All characters to the right of the pound sign are ignored.
The following is an example of a parameter file:
USERID=system/manager USER=HR # scan HR tables TOCHAR=al32utf8 ARRAY=4096000 PROCESS=2 # use two concurrent scan processes FEEDBACK=1000
The following table shows a summary of parameters for the Database Character Set Scanner. The rest of this section contains detailed descriptions of the parameters.
| Parameter | Default | Prompt | Description |
|---|---|---|---|
| USERID | - | yes | Username/password |
| FULL | N |
yes | Scan entire database |
| USER | - |
yes | Owner of the tables to be scanned |
| TABLE | - | yes | List of tables to scan |
| EXCLUDE | - | no | List of tables to exclude |
| TOCHAR | - | yes | New database character set name |
| FROMCHAR | - | no | Current database character set name |
| TONCHAR | - | no | New national character set name |
| FROMNCHAR | - | no | Current national character set name |
| ARRAY | 1024000 |
yes | Size of array fetch buffer |
| PROCESS | 1 |
yes | Number of concurrent scan processes |
| MAXBLOCKS | - | no | The maximum number of blocks that can be in a table without the table being split |
| CAPTURE | N |
no | Capture convertible data |
| COLUMN | - | no | List of columns to scan |
| QUERY | - | no | Query to apply to restrict output before scan |
| SUPPRESS | - | no | Maximum number of exceptions logged for each table |
| FEEDBACK | - | no | Report progress every n rows |
| BOUNDARIES | - | no | List of column size boundaries for summary report |
| LASTRPT | N |
no | Generate report of the previous database scan |
| LOG | scan |
no | Base file name for report files |
| PARFILE | - | no | Parameter file name |
| PRESERVE | N |
no | Preserve existing scan results |
| LCSD | N |
no | Enable language and character set detection |
| LCSDDATA | LOSSY |
no | Define the scope of the language and character set detection |
| HELP | N |
no | Show help screen |
ARRAY
| Property | Description |
|---|---|
| Default value | 1024000 |
| Minimum value | 4096 |
| Maximum value | Unlimited |
| Purpose | Specifies the size in bytes of the array buffer used to fetch data. The size of the array buffer determines the number of rows fetched by the Database Character Set Scanner at any one time. |
The following formula estimates the number of rows fetched at one time for a given table:
rows fetched = (ARRAY value) / [(sum of all the CHAR and VARCHAR2 column sizes) + (number of CLOB columns * 4000) + (number of VARRAY columns * 4000)]
For example, suppose table A contains two CHAR columns (5 bytes and 10 bytes), two VARCHAR2 columns (100 bytes and 200 bytes), and one CLOB column. If ARRAY=1024000 (the default), then the number of rows fetched is calculated as follows:
1024000/[5 + 10 + 100 + 200 + (1*4000) + (0*4000)] = 237.3
The Database Character Set Scanner can fetch 23 rows of data at one time from table A.
If the sum in the denominator exceeds the value of the ARRAY parameter, then the Database Character Set Scanner fetches only one row at a time. Tables with LONG columns are fetched only one row at a time.
This parameter affects the duration of a database scan. In general, the larger the size of the array buffer, the shorter the duration time. Each scan process allocates the specified size of array buffer.
BOUNDARIES
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the list of column boundary sizes that are used for an application data conversion summary report. This parameter is used to locate the distribution of the application data for the CHAR, VARCHAR2, NCHAR, and NVARCHAR2 data types. |
For example, if you specify a BOUNDARIES value of (10, 100, 1000), then the application data conversion summary report produces a breakdown of the CHAR data into the following groups by their column length, CHAR(1..10), CHAR(11..100) and CHAR(101..1000). The behavior is the same for the VARCHAR2, NCHAR, and NVARCHAR2 data types.
| Property | Description |
|---|---|
| Default value | N |
| Range of values | Y or N |
| Purpose | Indicates whether to capture the information on the individual convertible rows, as well as the default of storing only the exception rows. Information regarding the convertible rows is written to the CSM$ERRORS table if the CAPTURE parameter is set to Y. It records the data that needs to be converted during the conversion to the target character set. When CAPTURE is set to Y, the data dictionary CONVERTIBLE data cells are also listed in the database scan individual exception report scan.err. With CAPTURE set to Y, the amount of time required to complete the scan can increase and more storage space may be required. |
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the names of the columns to be scanned |
When this parameter is specified, the Database Character Set Scanner scans the specified columns. You can specify the following when you specify the name of the column:
schemaname specifies the names of the user's schema from which to scan the table
tablename specifies the name of the table from which to scan the column
columnname specifies the name of the column to be scanned
For example, the following command scans the columns LASTNAME and FIRSTNAME in the hr sample schema:
CSSCAN system/manager COLUMN=(HR.EMPLOYEES.LASTNAME, HR.EMPLOYEES.FIRSTNAME) ...
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the names of the tables to be excluded from the scan |
When this parameter is specified, the Database Character Set Scanner excludes the specified tables from the scan. You can specify the following when you specify the name of the table:
schemaname specifies the name of the user's schema from which to exclude the table
tablename specifies the name of the table or tables to be excluded
For example, the following command scans all of the tables that belong to the hr sample schema except for the employees and departments tables:
CSSCAN system/manager USER=HR EXCLUDE=(HR.EMPLOYEES , HR.DEPARTMENTS) ...
FEEDBACK
| Property | Description |
|---|---|
| Default value | None |
| Minimum value | 100 |
| Maximum value | 100000 |
| Purpose | Specifies that the Database Character Set Scanner should display a progress meter in the form of a dot for every N number of rows scanned |
For example, if you specify FEEDBACK=1000, then the Database Character Set Scanner displays a dot for every 1000 rows scanned. The FEEDBACK value applies to all tables being scanned. It cannot be set for individual tables.
FROMCHAR
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the current character set name for CHAR, VARCHAR2, LONG, and CLOB data types in the database. By default, the Database Character Set Scanner assumes the character set for these data types to be the database character set. |
Use this parameter to override the default database character set definition for CHAR, VARCHAR2, LONG, and CLOB data in the database.
FROMNCHAR
| Property | Description |
|---|---|
| Default value | The current database character set. |
| Purpose | Specifies the current national database character set name for NCHAR, NVARCHAR2, and NCLOB data types in the database. By default, the Database Character Set Scanner assumes the character set for these data types to be the database national character set. |
Use this parameter to override the default database character set definition for NCHAR, NVARCHAR2, and NCLOB data in the database.
FULL
| Property | Description |
|---|---|
| Default value | N |
| Range of values | Y or N |
| Purpose | Indicates whether to perform the full database scan (that is, to scan the entire database including the data dictionary). Specify FULL=Y to scan in full database mode. |
See Also:
"Scan Modes in the Database Character Set Scanner" for more information about full database scansHELP
| Property | Description |
|---|---|
| Default value | N |
| Range of values | Y or N |
| Purpose | Displays a help message with the descriptions of the Database Character Set Scanner parameters |
LASTRPT
| Property | Description |
|---|---|
| Default value | N |
| Range of values | Y or N |
| Purpose | Indicates whether to regenerate the Database Character Set Scanner reports based on statistics gathered from the previous database scan |
If LASTRPT=Y is specified, then the Database Character Set Scanner does not scan the database, but creates the report files using the information left by the previous database scan session instead.
If LASTRPT=Y is specified, then only the USERID, BOUNDARIES, and LOG parameters take effect.
LCSD
| Property | Description |
|---|---|
| Default value | N |
| Range of values | Y or N |
| Purpose | Indicates whether to apply language and character set detection during scanning |
If LCSD=Y is specified, then the Database Character Set Scanner (CSSCAN) performs language and character set detection on the data cells categorized by the LCSDDATA parameter. The accuracy of the detection depends greatly on the size and the quality of the text being analyzed. The ideal case is literary text of one single language with no spelling or grammatical errors. Data cells that contain a mixture of languages or character sets or text such as addresses and names can yield poor results. When CSSCAN cannot determine the most likely language and character set, it may return up to three most likely languages and character sets for each cell. In some cases it may return none. CSSCAN ignores any data cells with less than 10 bytes of data and returns UNKNOWN for their language and character set.
The language and character set detection is a statistically-based technology, so its accuracy varies depending on the quality of the input data. The goal is to provide CSSCAN users with additional information about unknown data inside the database. It is important for CSSCAN users to review the detection results and the data itself before migrating the data to another character set.
Note that language and character set detection can affect the performance of the Database Character Set Scanner, depending on the amount of data that is being analyzed.
LCSDDATA
| Property | Description |
|---|---|
| Default value | LOSSY |
| Range of values | LOSSY, TRUNCATION, CONVERTIBLE, CHANGELESS, ALL |
| Purpose | Specifies the scope of the language and character set detection. The default is to apply the detection to only the LOSSY data cells. |
This parameter takes effect only when LCSD=Y is specified. For example, if LCSD=Y and LCSDDATA=LOSSY, CONVERTIBLE, then the Database Character Set Scanner tries to detect the character sets and languages of the data cells that are either LOSSY or CONVERTIBLE. Data that is classified as CHANGELESS and TRUNCATION will not be processed. Setting LCSDDATA=ALL results in language and character set detection for all data cells scanned in the current session.
After language and character set detection has been applied to CONVERTIBLE and TRUNCATION data cells, some data cells may change from their original classification to LOSSY. This occurs when the character set detection process determines that the character set of these data cells is not the character set specified in the FROMCHAR parameter.
LOG
| Property | Description |
|---|---|
| Default value | scan |
| Purpose | Specifies a base file name for the following Database Character Set Scanner report files:
|
By default, the Database Character Set Scanner generates the three text files, scan.txt, scan.err, and scan.out in the current directory.
MAXBLOCKS
| Property | Description |
|---|---|
| Default value | None |
| Minimum value | 1000 |
| Maximum value | Unlimited |
| Purpose | Specifies the maximum block size for each table, so that large tables can be split into smaller chunks for the Database Character Set Scanner to process |
For example, if the MAXBLOCKS parameter is set to 1000, then any tables that are greater than 1000 blocks in size are divided into n chunks, where n=CEIL(table block size/1000).
Dividing large tables into smaller pieces is beneficial only when the number of processes set with PROCESS is greater than 1. If the MAXBLOCKS parameter is not set, then the Database Character Set Scanner attempts to split up large tables based on its own optimization rules.
PARFILE
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the name for a file that contains a list of Database Character Set Scanner parameters |
| Property | Description |
|---|---|
| Default value | N |
| Range of values | Y or N |
| Purpose | Indicates whether to preserve the statistics gathered from the previous scan session |
If PRESERVE=Y is specified, then the Database Character Set Scanner preserves all of the statistics from the previous scan. It adds (if PRESERVE=Y) or overwrites (if PRESERVE=N) the new statistics for the tables being scanned in the current scan request.
PROCESS
| Property | Description |
|---|---|
| Default value | 1 |
| Minimum value | 1 |
| Maximum value | 32 |
| Purpose | Specifies the number of concurrent scan processes to utilize for the database scan |
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Applies a filter to restrict the data to be scanned by specifying a clause for a SELECT statement, which is applied to all tables and columns in the scanner session |
The value of the query parameter is a string that contains a WHERE clause for a SELECT statement that will be applied to all tables and columns listed in the TABLE and COLUMN parameters.
Only one query clause is allowed per scan session. The QUERY parameter is only applicable when performing table or column scans. The parameter will be ignored when performing a Full database or a User scan. QUERY can be applied to multiple tables and columns scans, however, the identical WHERE clause will be appended to all specified tables and columns.
For example, the following command scans the employess who were hired within the last 30 days:
CSSCAN system/manager TABLE=HR.EMPLOYEES QUERY= 'hire_date > SYSDATE - 180' ...
Note that the WHERE clause is not required inside the QUERY parameter. CSSCAN will automatically remove the WHERE clause if it is found to be the first five characters in the QUERY parameter.
SUPPRESS
| Property | Description |
|---|---|
| Default value | Unset (results in unlimited number of rows) |
| Minimum value | 0 |
| Maximum value | Unlimited |
| Purpose | Specifies the maximum number of data exceptions being logged for each table |
The Database Character Set Scanner inserts information into the CSM$ERRORS table when an exception is found in a data cell. The table grows depending on the number of exceptions reported.
This parameter is used to suppress the logging of individual exception information after a specified number of exceptions are inserted for each table. For example, if SUPPRESS is set to 100, then the Database Character Set Scanner records a maximum of 100 exception records for each table.
TABLE
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the names of the tables to scan |
You can specify the following when you specify the name of the table:
schemaname specifies the name of the user's schema from which to scan the table
tablename specifies the name of the table or tables to be scanned
For example, the following command scans the employees and departments tables in the HR sample schema:
CSSCAN system/manager TABLE=(HR.EMPLOYEES, HR.DEPARTMENTS)
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies a target database character set name for the CHAR, VARCHAR2, LONG, and CLOB data |
TONCHAR
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies a target database character set name for the NCHAR, NVARCHAR2, and NCLOB data |
If you do not specify a value for TONCHAR, then the Database Character Set Scanner does not scan NCHAR, NVARCHAR2, and NCLOB data.
USER
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the owner of the tables to be scanned |
If the USER parameter is specified, then the Database Character Set Scanner scans all tables belonging to the specified owner. For example, the following statement scans all tables belonging to HR:
CSSCAN system/manager USER=hr ...
USERID
| Property | Description |
|---|---|
| Default value | None |
| Purpose | Specifies the username and password (and optional connect string) of the user who scans the database. If you omit the password, then the Database Character Set Scanner prompts you for it |
The following formats are all valid:
username/password username/password@connect_string username username@connect_string
The following examples show you how to use the command-line and parameter-file methods for the Full Database, User, Single Table, and Column scan modes.
The following examples show how to scan the full database to see the effects of migrating it to AL32UTF8. These examples assume that the current database character set is WE8ISO8859P1.
Example 12-6 Database Scan Using the Parameter-File Method
% csscan system/manager parfile=param.txt
The param.txt file contains the following information:
full=y tochar=al32utf8 array=4096000 process=4
Example 12-7 Database Scan Using the Command-Line Method
% csscan system/manager full=y tochar=al32utf8 array=4096000 process=4
The scan.out file shows which tables were scanned. The default file name for the report can be changed by using the LOG parameter.
See Also:
"LOG"Database Character Set Scanner vx.x : Release xx.x.x.x.x - Production Copyright (c) 1982, 200x, Oracle. All rights reserved. Connected to: Oracle Database xxx Enterprise Edition Release xx.x.x.x.x - Production With the Partitioning and Data Mining options Enumerating tables to scan... . process 1 scanning SYS.SOURCE$[AAAABHAABAAAAJqAAA] . process 2 scanning SYS.TAB$[AAAAACAABAAAAA0AAA] . process 2 scanning SYS.CLU$[AAAAACAABAAAAA0AAA] . process 2 scanning SYS.ICOL$[AAAAACAABAAAAA0AAA] . process 2 scanning SYS.COL$[AAAAACAABAAAAA0AAA] . process 1 scanning SYS.IND$[AAAAACAABAAAAA0AAA] . process 1 scanning SYS.TYPE_MISC$[AAAAACAABAAAAA0AAA] . process 1 scanning SYS.LOB$[AAAAACAABAAAAA0AAA] . . . . process 1 scanning IX.AQ$_ORDERS_QUEUETABLE_G . process 2 scanning IX.AQ$_ORDERS_QUEUETABLE_I Creating Database Scan Summary Report... Creating Individual Exception Report... Scanner terminated successfully.
The following examples show how to scan the user tables to see the effects of migrating them to AL32UTF8. These examples assume that the current database character set is US7ASCII, but the actual data stored is in Western European WE8MSWIN1252 encoding.
Example 12-8 User Scan with Parameter-File Method
% csscan system/manager parfile=param.txt
The param.txt file contains the following information:
user=hr fromchar=we8mswin1252 tochar=al32utf8 array=4096000 process=1
Example 12-9 User Scan with Command-Line Method
% csscan system/manager user=hr fromchar=we8mswin1252
tochar=al32utf8 array=4096000 process=1
The scan.out file shows which tables were scanned.
Database Character Set Scanner vx.x : Release xx.x.x.x.x - Production Copyright (c) 1982, 200x, Oracle. All rights reserved. Connected to: Oracle Database xxx Enterprise Edition Release xx.x.x.x.x - Production With the Partitioning and Data Mining options Copyright (c) 1983, 200x Oracle. All rights reserved. Enumerating tables to scan... . process 1 scanning HR.JOBS . process 1 scanning HR.DEPARTMENTS . process 1 scanning HR.JOB_HISTORY . process 1 scanning HR.EMPLOYEES Creating Database Scan Summary Report... Creating Individual Exception Report... Scanner terminated successfully.
The following examples show how to scan a single table to see the effects of migrating it to WE8MSWIN1252. These examples assume that the current database character set is in US7ASCII. Language and character set detection is performed on the LOSSY data cells.
Example 12-10 Single Table Scan with Parameter-File Method
% csscan system/manager parfile=param.txt
The param.txt file contains the following information:
table=hr.employees tochar=we8mswin1252 array=4096000 process=1 suppress=100 lcsd=y
Example 12-11 Single Table Scan with Command-Line Method
% csscan system/manager table=hr.employees tochar=we8mswin1252 array=4096000 process=1 supress=100 lcsd=y
The scan.out file shows which tables were scanned.
Database Character Set Scanner vx.x : Release xx.x.x.x.x - Production Copyright (c) 1982, 200x, Oracle. All rights reserved. Connected to: Oracle Database xxx Enterprise Edition Release xx.x.x.x.x - Production With the Partitioning and Data Mining options Copyright (c) 1983, 200x Oracle. All rights reserved. . process 1 scanning HR.EMPLOYEES Creating Database Scan Summary Report... Creating Individual Exception Report... Scanner terminated successfully.
The following example shows how to scan a single table to see the effect of migrating it to WE8MSWIN1252. Before scanning, a query is run against the table to limit the rows that will be scanned. This example assumes the current database character set is in US7ASCII. Language and character set detection is performed on the LOSSY data cells.
Example 12-12 Single Table Scan with Parameter-File Method, Showing the Effect of Migrating to WE8MSWIN1252
% csscan system/manager parfile=param.txt
The param.txt file contains the following information:
table=hr.employees query='hire_date > SYSDATE - 180' tochar=we8mswin1252 array=4096000 process=1 suppress=100 lcsd=y
The scan.out file shows which tables were scanned.
Database Character Set Scanner vx.x : Release xx.x.x.x.x - Production Copyright (c) 1982, 200x, Oracle. All rights reserved. Connected to: Oracle Database xxx Enterprise Edition Release xx.x.x.x.x - Production With the Partitioning and Data Mining options Copyright (c) 1983, 200x Oracle. All rights reserved. . process 1 scanning HR.EMPLOYEES Creating Database Scan Summary Report... Creating Individual Exception Report... Scanner terminated successfully.
The following example shows how to scan columns within a table to see the effects of migrating it to WE8MSWIN1252. This example assumes the current database character set is in US7ASCII. Language and character set detection is performed on the LOSSY data cells.
Example 12-14 Column Scan with Parameter-File Method
% csscan system/manager parfile=param.txt
The param.txt file contains the following information:
column=(hr.employees.lastname, hr.employees.firstname) tochar=we8mswin1252 array=4096000 process=1 suppress=100 lcsd=y
Example 12-15 Column Scan with Command-Line Method
% csscan system/manager column=(hr.employees.lastname, hr.employees.firstname) tochar=we8mswin1252 array=4096000 process=1 supress=100 lcsd=y
The scan.out file shows which tables were scanned.
Database Character Set Scanner vx.x : Release xx.x.x.x.x - Production Copyright (c) 1982, 200x, Oracle. All rights reserved. Connected to: Oracle Database xxx Enterprise Edition Release xx.x.x.x.x - Production With the Partitioning and Data Mining options Copyright (c) 1983, 200x Oracle. All rights reserved. . process 1 scanning HR.EMPLOYEES Creating Database Scan Summary Report... Creating Individual Exception Report... Scanner terminated successfully.
The Database Character Set Scanner generates two reports for each scan:
The Database Scan Summary Report is found in the scan.txt file. The Database Scan Individual Exception Report is found in the scan.err file.
The default file names for the reports can be changed by using the LOG parameter.
See Also:
"LOG"The scan.txt file contains the Database Scan Summary Report. The following output is an example of the report header. This section contains the time when each process of the scan was performed.
Database Scan Summary Report
Time Started : 200x-12-16 20:35:56
Time Completed: 200x-12-16 20:37:31
Process ID Time Started Time Completed
---------- -------------------- --------------------
1 200x-12-16 20:36:07 2002-12-16 20:37:30
2 200x-12-16 20:36:07 2002-12-16 20:37:30
---------- -------------------- --------------------
The report consists of the following sections:
The information available for each section depends on the type of scan and the parameters you select.
This section reports on the current database size as well as identifying the amount of potential data expansion after the character set migration.
The following output is an example.
Tablespace Used Free Total Expansion ------------------------- --------------- --------------- --------------- --------------- SYSTEM 206.63M 143.38M 350.00M 588.00K SYSAUX 8.25M 131.75M 140.00M .00K ------------------------- --------------- --------------- --------------- --------------- Total 214.88M 275.13M 490.00M 588.00K The size of the largest CLOB is 57370 bytes
This section describes the parameters selected and the type of scan you chose. The following output is an example.
Parameter Value ------------------------------ ------------------------------------------------ CSSCAN Version v2.1 Instance Name rdbms06 Database Version 10.2.0.0.0 Scan type Full database Scan CHAR data? YES Database character set WE8ISO8859P1 FROMCHAR WE8ISO8859P1 TOCHAR AL32UTF8 Scan NCHAR data? NO Array fetch buffer size 1024000 Number of processes 2 Capture convertible data? NO Charset Language Detections Yes Charset Language Parameter LOSSY ------------------------------ ------------------------------------------------
This section indicates the feasibility of the database character set migration. There are two basic criteria that determine the feasibility of the character set migration of the database. One is the condition of the data dictionary and the other is the condition of the application data.
The Scan Summary section consists of two status lines: one line reports on the data dictionary, and the other line reports on the application data.
The following is sample output from the Scan Summary:
All character type data in the data dictionary are convertible to the new character set Some character type application data are not convertible to the new character set
Table 12-1 shows the types of status that can be reported for the data dictionary and application data.
Table 12-1 Possible Status of the Data Dictionary and Application Data
| Data Dictionary Status | Application Data Status |
|---|---|
|
All character-type data in the data dictionary remains the same in the new character set. |
All character-type application data remains the same in the new character set. |
|
All character-type data in the data dictionary is convertible to the new character set. |
All character-type application data is convertible to the new character set. |
|
Some character-type data in the data dictionary is not convertible to the new character set. |
Some character-type application data is not convertible to the new character set. |
When all data remains the same in the new character set, it means that the encoding values of the original character set are identical in the target character set. For example, ASCII data is stored using the same binary values in both WE8ISO8859P1 and AL32 UTF8. In this case, the database character set can be migrated using the CSALTER script.
If all the data is convertible to the new character set, then the data can be safely migrated using the Export and Import utilities. However, the migrated data will have different encoding values in the target character set.
See Also:
"Database Scan Individual Exception Report" for more information about non-convertible data
This section contains the statistics about the conversion of the data in the data dictionary. The numbers of data cells with each type of status are reported by data type. To achieve a comprehensive data dictionary conversion summary, you need to use a full database scan.
Table 12-2 describes the possible types of status of a data cell.
Table 12-2 Possible Status of Data
| Status | Description |
|---|---|
|
|
Data remains the same in the new character set |
|
|
Data can be successfully converted to the new character set |
|
|
Data will be truncated if conversion takes place |
|
|
Character data will be lost if conversion takes place |
In order to provide more information on how to convert data in the data dictionary, the Data Dictionary Conversion Summary report has been divided into two parts: Data Dictionary Tables, and XML CSX Dictionary Tables. Compact binary XML (CSX) is a new format for XML documents in XML DB in Oracle Database 11g Release 2 (11.2). When you insert an XML document into a CSX column, the database saves CSX data into a BLOB column in the application data part. Simultaneously, the database saves the data into the tables of the XDB user, which belong to data dictionary. In the data dictionary, these tables are called as XML CSX Dictionary Tables.
Similarly, the tables for "Distribution of Convertible, Truncated and Lossy Data by Table" and "Distribution of Convertible, Truncated and Lossy Data by Column" have been organized into three parts, respectively: Data Dictionary Tables, XML CSX Dictionary Tables, and Application Data.
The following output is an example of the expanded Data Dictionary Conversion Summary report.
Database Scan Summary Report
Time Started : 2006-08-15 01:13:24
Time Completed: 2006-08-15 01:16:32
Process ID Time Started Time Completed
---------- -------------------- --------------------
1 2006-08-15 01:13:28 2006-08-15 01:16:30
---------- -------------------- --------------------
[Database Size]
Tablespace Used Free Total Expansion
------------------------- --------------- --------------- --------------- ---------------
SYSTEM 542.77M 9.82M 552.59M 1.41M
SYSAUX 80.00M .00K 80.00M 574.00K
TEMP .00K .00K .00K .00K
XDB_RESINFO 51.81M 48.19M 100.00M 18.00K
XDB_TEMP .00K .00K .00K .00K
------------------------- --------------- --------------- --------------- ---------------
Total 674.59M 58.01M 732.59M 1.98M
The size of the largest CLOB is 61115 bytes
[Database Scan Parameters]
Parameter Value
------------------------------ ------------------------------------------------
CSSCAN Version v2.1
Instance Name cm2
Database Version 11.1.0.0.0
Scan type Full database
Scan CHAR data? YES
Database character set WE8ISO8859P1
FROMCHAR we8iso8859p1
TOCHAR utf8
Scan NCHAR data? YES
NCHAR character set AL16UTF16
FROMNCHAR al16utf16
TONCHAR utf8
Array fetch buffer size 102400
Number of processes 1
Capture convertible data? NO
------------------------------ ------------------------------------------------
[Scan Summary]
All character type data in the data dictionary are convertible to the new character set
All character type application data are convertible to the new character set
[Data Dictionary Conversion Summary]
Data Dictionary Tables:
Datatype Changeless Convertible Truncation Lossy
--------------------- ---------------- ---------------- ---------------- ----------------
VARCHAR2 3,294,477 0 0 0
CHAR 1,941 0 0 0
LONG 133,551 0 0 0
CLOB 21,633 841 0 0
NVARCHAR2 0 0 0 0
NCHAR 0 0 0 0
NCLOB 0 0 0 0
VARRAY 26,965 0 0 0
--------------------- ---------------- ---------------- ---------------- ----------------
Total 3,478,567 841 0 0
Total in percentage 99.976% 0.024% 0.000% 0.000%
The data dictionary can be safely migrated using the CSALTER script
XML CSX Dictionary Tables:
Datatype Changeless Convertible Truncation Lossy
--------------------- ---------------- ---------------- ---------------- ----------------
VARCHAR2 173 8 0 0
CHAR 0 0 0 0
LONG 0 0 0 0
CLOB 0 0 0 0
NVARCHAR2 0 0 0 0
NCHAR 0 0 0 0
NCLOB 0 0 0 0
VARRAY 0 0 0 0
--------------------- ---------------- ---------------- ---------------- ----------------
Total 173 8 0 0
Total in percentage 95.580% 4.420% 0.000% 0.000%
[Application Data Conversion Summary]
Datatype Changeless Convertible Truncation Lossy
--------------------- ---------------- ---------------- ---------------- ----------------
VARCHAR2 36,011 0 0 0
CHAR 5,533 0 0 0
LONG 0 0 0 0
CLOB 27 26 0 0
NVARCHAR2 0 17,280 0 0
NCHAR 0 0 0 0
NCLOB 4 0 0 0
VARRAY 319 0 0 0
--------------------- ---------------- ---------------- ---------------- ----------------
Total 41,894 17,306 0 0
Total in percentage 70.767% 29.233% 0.000% 0.000%
[Distribution of Convertible, Truncated and Lossy Data by Table]
Data Dictionary Tables:
USER.TABLE Convertible Truncation Lossy
-------------------------------------------------- ---------------- ---------------- ----------------
SYS.EXTERNAL_TAB$ 1 0 0
SYS.METASTYLESHEET 145 0 0
SYS.RULE$ 1 0 0
SYS.SCHEDULER$_EVENT_LOG 26 0 0
SYS.WRH$_SQLTEXT 239 0 0
SYS.WRH$_SQL_PLAN 217 0 0
SYS.WRI$_ADV_DIRECTIVE_META 5 0 0
SYS.WRI$_ADV_OBJECTS 1 0 0
SYS.WRI$_DBU_FEATURE_METADATA 94 0 0
SYS.WRI$_DBU_FEATURE_USAGE 3 0 0
SYS.WRI$_DBU_HWM_METADATA 17 0 0
SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY 71 0 0
SYS.WRI$_REPT_FILES 4 0 0
XDB.XDB$RESCONFIG 9 0 0
XDB.XS$PRINCIPALS 1 0 0
XDB.XS$SECURITYCLASS 7 0 0
-------------------------------------------------- ---------------- ---------------- ----------------
XML CSX Dictionary Tables:
USER.TABLE Convertible Truncation Lossy
-------------------------------------------------- ---------------- ---------------- ----------------
XDB.X$QN0S0VE2C21FAJ8E0G5PHDLAO3BO 8 0 0
-------------------------------------------------- ---------------- ---------------- ----------------
Application Data:
USER.TABLE Convertible Truncation Lossy
-------------------------------------------------- ---------------- ---------------- ----------------
OE.PRODUCT_DESCRIPTIONS 17,280 0 0
OE.WAREHOUSES 4 0 0
PM.ONLINE_MEDIA 14 0 0
PM.PRINT_MEDIA 8 0 0
-------------------------------------------------- ---------------- ---------------- ----------------
[Distribution of Convertible, Truncated and Lossy Data by Column]
Data Dictionary Tables:
USER.TABLE|COLUMN Convertible Truncation Lossy
-------------------------------------------------- ---------------- ---------------- ----------------
SYS.EXTERNAL_TAB$|PARAM_CLOB 1 0 0
SYS.METASTYLESHEET|STYLESHEET 145 0 0
SYS.RULE$|CONDITION 1 0 0
SYS.SCHEDULER$_EVENT_LOG|ADDITIONAL_INFO 26 0 0
SYS.WRH$_SQLTEXT|SQL_TEXT 239 0 0
SYS.WRH$_SQL_PLAN|OTHER_XML 217 0 0
SYS.WRI$_ADV_DIRECTIVE_META|DATA 5 0 0
SYS.WRI$_ADV_OBJECTS|ATTR4 1 0 0
SYS.WRI$_DBU_FEATURE_METADATA|INST_CHK_LOGIC 11 0 0
SYS.WRI$_DBU_FEATURE_METADATA|USG_DET_LOGIC 83 0 0
SYS.WRI$_DBU_FEATURE_USAGE|FEATURE_INFO 3 0 0
SYS.WRI$_DBU_HWM_METADATA|LOGIC 17 0 0
SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY|EXPRESSION 71 0 0
SYS.WRI$_REPT_FILES|SYS_NC00005$ 4 0 0
XDB.XDB$RESCONFIG|XMLDATA 9 0 0
XDB.XS$PRINCIPALS|XMLDATA 1 0 0
XDB.XS$SECURITYCLASS|XMLDATA 7 0 0
-------------------------------------------------- ---------------- ---------------- ----------------
XML CSX Dictionary Tables:
USER.TABLE|COLUMN Convertible Truncation Lossy
-------------------------------------------------- ---------------- ---------------- ----------------
XDB.X$QN0S0VE2C21FAJ8E0G5PHDLAO3BO|LOCALNAME 8 0 0
-------------------------------------------------- ---------------- ---------------- ----------------
Application Data:
USER.TABLE|COLUMN Convertible Truncation Lossy
-------------------------------------------------- ---------------- ---------------- ----------------
OE.PRODUCT_DESCRIPTIONS|TRANSLATED_DESCRIPTION 8,640 0 0
OE.PRODUCT_DESCRIPTIONS|TRANSLATED_NAME 8,640 0 0
OE.WAREHOUSES|SYS_NC00003$ 4 0 0
PM.ONLINE_MEDIA|SYS_NC00042$ 7 0 0
PM.ONLINE_MEDIA|SYS_NC00062$ 7 0 0
PM.PRINT_MEDIA|AD_FINALTEXT 4 0 0
PM.PRINT_MEDIA|AD_SOURCETEXT 4 0 0
-------------------------------------------------- ---------------- ---------------- ----------------
[Indexes to be Rebuilt] USER.INDEX on USER.TABLE(COLUMN) ----------------------------------------------------------------------------------------- SYS.I_WRI$_OPTSTAT_HH_ST on SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY(SYS_NC00024$) SYS.I_WRI$_OPTSTAT_HH_OBJ_ICOL_ST on SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY(SYS_NC00024$) SYS.I_WRI$_OPTSTAT_HH_OBJ_ICOL_ST on SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY(OBJ#) SYS.I_WRI$_OPTSTAT_HH_OBJ_ICOL_ST on SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY(INTCOL#) SYS.I_WRI$_OPTSTAT_HH_OBJ_ICOL_ST on SYS.WRI$_OPTSTAT_HISTHEAD_HISTORY(COLNAME) OE.PROD_NAME_IX on OE.PRODUCT_DESCRIPTIONS(TRANSLATED_NAME) XDB.X$QQ0S0VE2C21FAJ8E0G5PHDLAO3BO on XDB.X$QN0S0VE2C21FAJ8E0G5PHDLAO3BO(NMSPCID) XDB.X$QQ0S0VE2C21FAJ8E0G5PHDLAO3BO on XDB.X$QN0S0VE2C21FAJ8E0G5PHDLAO3BO(LOCALNAME) XDB.X$QQ0S0VE2C21FAJ8E0G5PHDLAO3BO on XDB.X$QN0S0VE2C21FAJ8E0G5PHDLAO3BO(FLAGS) -----------------------------------------------------------------------------------------
The following output is an example of the Data Dictionary Conversion Summary report in previous releases.
Datatype Changeless Convertible Truncation Lossy --------------------- ---------------- ---------------- ---------------- ---------------- VARCHAR2 1,214,557 0 0 0 CHAR 967 0 0 0 LONG 88,657 0 0 0 CLOB 138 530 0 0 VARRAY 18 0 0 0 --------------------- ---------------- ---------------- ---------------- ---------------- Total 1,304,337 530 0 0 Total in percentage 99.959% 0.041% 0.000% 0.000% The data dictionary can be safely migrated using the CSALTER script.
If the numbers of data cells recorded in the Convertible, Truncation, and Lossy columns are zero in the data dictionary tables and the XML CSX dictionary tables, then no data conversion is required to migrate the data dictionary from the FROMCHAR character set to the TOCHAR character set.
If the numbers in the Truncation and Lossy columns are zero and some numbers in the Convertible columns are not zero in both data dictionary tables and XML CSX dictionary tables, then all data in the data dictionary is convertible to the new character set. However, it is dangerous to convert the data in the data dictionary without understanding their impact on the database. All convertible cells in the XML CSX dictionary tables can be safely converted, so they are output explicitly out of the data dictionary tables. The CSALTER script can convert some of the convertible cells in the data dictionary. The message that follows the conversion summary table indicates whether this conversion can be supported by the CSALTER script.
If the numbers in the Lossy column are not zero in the data dictionary tables or XML CSX dictionary tables, then there is data in the data dictionary that is not convertible. Therefore, it is not feasible to migrate the current database to the new character because the export and import processes cannot convert the data into the new character set. For example, you might have a table name with invalid characters or a PL/SQL procedure with a comment line that includes data that cannot be mapped to the new character set. These changes to schema objects must be corrected manually before migration to a new character set.
If the numbers in the Truncation column are not zero in the data dictionary tables or XML CSX dictionary tables, then the export and import process will truncate the data.
This section contains the statistics on conversion summary of the application data. The numbers of data cells with each type of status are reported by data type. Table 12-2 describes the types of status that can be reported.
The following output is an example.
Datatype Changeless Convertible Truncation Lossy --------------------- ---------------- ---------------- ---------------- ---------------- VARCHAR2 37,757 3 0 0 CHAR 6,404 0 0 0 LONG 4 0 0 0 CLOB 23 20 0 1 VARRAY 319 0 0 0 --------------------- ---------------- ---------------- ---------------- ---------------- Total 44,507 23 0 1 Total in percentage 99.946% 0.051% 0% 0.002%
This section contains the conversion summary of the CHAR and VARCHAR2 application data. The number of data cells with each type of status are reported by column size boundaries specified by the BOUNDARIES parameter. Table 12-2 describes the possible types of status. This information is available only when the BOUNDARIES parameter is specified. The following output is an example.
Datatype Changeless Convertible Truncation Lossy --------------------- ---------------- ---------------- ---------------- ---------------- VARCHAR2(1..30) 28,702 2 0 0 VARCHAR2(31..4000) 9,055 1 0 0 --------------------- ---------------- ---------------- ---------------- ---------------- CHAR(1..30) 6,404 0 0 0 CHAR(31..4000) 0 0 0 0 --------------------- ---------------- ---------------- ---------------- ---------------- Total 44,161 3 0 0
This section shows how Convertible, Truncation, and Lossy data is distributed within the database. The statistics are reported by table. If the list contains only a few rows, then the Convertible data is localized. If the list contains many rows, then the Convertible data occurs throughout the database. The following output is an example.
USER.TABLE Convertible Truncation Lossy ---------------------------- ---------------- ---------------- ---------------- HR.EMPLOYEES 1 0 0 OE.CUSTOMERS 2 0 0 PM.ONLINE_MEDIA 13 0 0 PM.PRINT_MEDIA 7 0 1 SYS.EXTERNAL_TAB$ 1 0 0 SYS.METASTYLESHEET 80 0 0 ---------------------------- ---------------- ---------------- ----------------
This section shows how Convertible, Truncation, and Lossy data is distributed within the database. The statistics are reported by column. The following output is an example.
USER.TABLE|COLUMN Convertible Truncation Lossy ------------------------------------- ---------------- ---------------- ---------------- HR.EMPLOYEES|FIRST_NAME 1 0 0 OE.CUSTOMERS|CUST_EMAIL 1 0 0 OE.CUSTOMERS|CUST_FIRST_NAME 1 0 0 PM.ONLINE_MEDIA|SYS_NC00042$ 6 0 0 PM.ONLINE_MEDIA|SYS_NC00062$ 7 0 0 PM.PRINT_MEDIA|AD_FINALTEXT 3 0 1 PM.PRINT_MEDIA|AD_SOURCETEXT 4 0 0 SYS.EXTERNAL_TAB$|PARAM_CLOB 1 0 0 SYS.METASTYLESHEET|STYLESHEET 80 0 0 ------------------------------------- ---------------- ---------------- ----------------
This generates a list of all the indexes that are affected by the database character set migration. These can be rebuilt after the data has been imported. The following output is an example.
USER.INDEX on USER.TABLE(COLUMN) -------------------------------------------------------------------------------------- HR.EMP_NAME_IX on HR.EMPLOYEES(FIRST_NAME) HR.EMP_NAME_IX on HR.EMPLOYEES(LAST_NAME) OE.CUST_EMAIL_IX on OE.CUSTOMERS(CUST_EMAIL) --------------------------------------------------------------------------------------
This section applies only to columns that are defined using character semantics. The Truncation Due to Character Semantics section identifies the number of data cells that would be truncated if they were converted to the target character set (for example, by the SQL CONVERT function or another inline conversion process) before the database character set is updated with the CSALTER script. If the data conversion occurs after the database character set is changed, then this section can be ignored.
For example, a VARCHAR2(5 char) column in a WE8MSWIN1252 database can store up to 5 characters, using 5 bytes. When these characters are migrated to AL32UTF8, the same 5 characters can expand to as much as 20 bytes in length. Because the physical byte limits allocated for the column are determined by the current database character set, this column must be manually expanded to 20 bytes before the data can be converted in the target character set. Alternatively, you can apply the character set conversion to this column after the database character set has been changed. Then the same VARCHAR2(5 char) definition will automatically allocate 20 bytes, and no special handling is required.
The following output is an example of the Truncation Due To Character Semantics section of the report.
USER.TABLE|COLUMN Truncation -------------------------------------------------- ---------------- HR.EMPLOYEES|FIRST_NAME 1
This section appears when the language and character set detection is turned on by the LCSD parameter. It displays a list of character sets detected by the Database Character Set Scanner. The character sets are ordered by occurrence. NUMBER refers to the number of data cells.
The following output is an example of the Character Set Detection Result section.
CHARACTER SET NUMBER PERCENTAGE ------------------------------ ---------------- ---------------- WE8MSWIN1252 38 97.436% UNKNOWN 1 2.564% ------------------------------ ---------------- ----------------
This section appears when the language and character set detection is turned on by the LCSD parameter. It displays a list of the languages detected by the Database Character Set Scanner. The languages are ordered by occurrence.
The following output is an example of the Language Detection Result Section.
LANGUAGE NUMBER PERCENTAGE ------------------------------ ---------------- ---------------- ENGLISH 36 92.308% FRENCH 2 5.128% UNKNOWN 1 2.564% ------------------------------ ---------------- ----------------
The scan.err file contains the Individual Exception Report. It consists of the following summaries:
This section describes the parameters and the type of scan chosen. The following output is an example.
Parameter Value ------------------------------ ------------------------------------------------ CSSCAN Version v2.1 Instance Name rdbms06 Database Version 10.2.0.0.0 Scan type Full database Scan CHAR data? YES Database character set WE8ISO8859P1 FROMCHAR WE8ISO8859P1 TOCHAR AL32UTF8 Scan NCHAR data? NO Array fetch buffer size 1024000 Number of processes 2 Capture convertible data? NO Charset Language Detection Yes Charset Language Parameter LOSSY ------------------------------ ------------------------------------------------
This section reports on whether data dictionary data is convertible or has exceptions. There are two types of exceptions:
exceed column size
lossy conversion
The following output is an example for a data dictionary that contains convertible data.
User : SYS Table : OBJ$ Column: NAME Type : VARCHAR2(30) Number of Exceptions : 0 Max Post Conversion Data Size: 30 ROWID Exception Type Size Cell Data(first 30 bytes) ------------------ ------------------ ----- ------------------------------ AAAAASAABAAAikLAAQ convertible Aufträge ------------------ ------------------ ----- ------------------------------
See Also:
"Application Data Individual Exceptions" for more information about exceptions
"How to Handle Convertible or Lossy Data in the Data Dictionary"
This report identifies the data with exceptions so that this data can be modified if necessary.
There are two types of exceptions:
exceed column size
The column size should be extended if the maximum column width has been surpassed. Otherwise, data truncation occurs.
lossy conversion
The data must be corrected before migrating to the new character set. Otherwise the invalid characters are converted to a replacement character. Replacement characters are usually specified as ? or ¿ or as a character that is linguistically similar to the source character.
The following example shows an individual exception report that illustrates some possible problems when changing the database character set from WE8ISO8859P1 to AL32UTF8.
User: USER1 Table: TEST Column: NAME Type: VARCHAR2(10) Number of Exceptions: 2 Max Post Conversion Data Size: 11 ROWID Exception Type Size Cell Data(first 30 bytes) ------------------ ------------------ ----- ------------------------------ AAAA2fAAFAABJwQAAg exceed column size 11 Ährenfeldt AAAA2fAAFAABJwQAAu lossy conversion órâclë8™ AAAA2fAAFAABJwQAAu exceed column size 11 órâclë8™ ------------------ ------------------ ----- ------------------------------
The values Ährenfeldt and órâclë8™ exceed the column size (10 bytes) because each of the characters Ä, ó, â, and ë occupies one byte in WE8ISO8859P1 but two bytes in AL32UTF8. The value órâclë8™ has lossy conversion to AL32UTF8 because the trademark sign ™ (code 153) is not a valid WE8ISO8859P1 character. It is a WE8MSWIN1252 character, which is a superset of WE8ISO8859P1.
You can view the data that has an exception by issuing a SELECT statement:
SELECT name FROM user1.test WHERE ROWID='AAAA2fAAFAABJwQAAu';
You can modify the data that has the exception by issuing an UPDATE statement:
UPDATE user1.test SET name = 'Oracle8 TM' WHERE ROWID='AAAA2fAAFAABJwQAAu';
If the language and character set detection option is enabled, then CSSCAN attempts to provide the most probable languages and character sets for the data cells specified by the LCSDDATA parameter.
The following example shows an individual exception report that illustrates language and character set detection results for lossy data cells when changing the database character set from US7ASCII to AL32UTF8.
User: USER2 Table: TEST Column: NAME Type: VARCHAR2(30) Number of Exceptions: 2 Max Post Conversion Data Size: 11 ROWID Exception Type Size Cell Data(first 30 bytes) Language & Character Set ------------------ ------------------ ----- --------------------------- ------------------------ AAAA2fAAFAABJwQAAt lossy conversion C'est français (French,UTF8) AAAA2fAAFAABJwQAAu lossy conversion Ciò è italiana (Italian,WE8MSWIN1252) ------------------ ------------------ ----- --------------------------- ------------------------
Unlike modifying user application data, updating and changing the contents of data dictionary tables directly is not supported. Updating the system tables without understanding the internal dependencies can lead to database corruption.
If the data dictionary is convertible, then the data cells are encoded in the FROMCHAR character set. Three common scenarios for the existence of convertible data in the data dictionary are:
CLOB data in the data dictionary
For single-byte character sets, CLOB data is stored in the database character set encoding. For multibyte character sets, CLOB data is stored in an internal Oracle Database format which is compatible with UCS-2. For example, the byte representation of the string 'ABC' stored inside a VARCHAR2 column in a US7ASCII database remains unchanged when migrated to AL32UTF8. The same string stored inside a CLOB column doubles in size and is stored completely differently. When migrating from a single-byte character set to a multibyte character set, CLOB data is never CHANGELESS.
XML CSX data in the data dictionary
All XML CSX data in the data dictionary can be safely converted like convertible application data.
Migrating a database to a character set that is a superset in the sense that it contains all of the characters of the original character set, but the binary values of some characters is not the same in the two character sets
This is similar to user application data whose data cells need to be manually converted to the new character set. A common cause of this is that the user 's object definitions (such as table names, column names, package names and package bodies) were created using non-ASCII characters. These are typically characters or symbols that are part of the user's native language.
The easiest approach to migrating convertible data dictionary data is to create a new database in the target character set and then re-create all of the data dictionary and schema definitions by exporting and importing. However, this method means creating a new database.
If you want to migrate the existing database instead of building a new one, then the CSALTER script is the simplest way to migrate convertible CLOB data inside the data dictionary and to change the existing database character set to the target character set.
For data dictionary CONVERTIBLE data cells that are not CLOB data, you must find the schema objects containing the convertible data. Then you can choose to do one of the following actions:
Amend the object definitions (such as removing non-ASCII characters from comments inside a package body) so that the data cells become CHANGELESS
Drop these objects from the database schema altogether and then re-create them after the database character set has been migrated to the target character set
LOSSY dictionary data cells require further examination of the data dictionary to see whether the current FROMCHAR character set is the actual character set of the database. If it is, you must correct these object definitions (such as removing the offending characters from comments inside a package body) so that the data cells become CHANGELESS and they can be migrated safely to the target character set.
Three SQL scripts are included with the Database Character Set Scanner to help users to locate the CONVERTIBLE and LOSSY data cells in the data dictionary:
The scripts are stored in the $ORACLE_HOME/nls/csscan/sql directory. They perform SQL SELECT operations on the SYS.SOURCE$, SYS.HISTGRM$ and SYS.RULE$ data dictionary tables so that the offending data dictionary objects can be identified.
The following example shows output from the analyze_source.sql script:
SQL> @$ORACLE_HOME/nls/csscan/sql/analyze_source.sql Table: SYS.SOURCE$ Error: CONVERTIBLE DATA no rows selected Table: SYS.SOURCE$ Error: EXCEPTIONAL DATA OWNER OBJECT_NAME OBJECT_TYPE EXCEPTIONAL ----------- -------------- ------------- ----------- SCOTT FOO FUNCTION 1
This section describes storage and performance issues in the Database Character Set Scanner. It contains the following topics:
Storage Considerations for the Database Character Set Scanner
Performance Considerations for the Database Character Set Scanner
Recommendations and Restrictions for the Database Character Set Scanner
This section describes the size and the growth of the Database Character Set Scanner's system tables, and explains the approach to maintain them. There are three system tables that can increase rapidly depending on the nature of the data stored in the database.
You may want to assign a large tablespace to the user CSMIG by amending the csminst.sql script. By default, the SYSTEM tablespace is assigned to the user CSMIG.
This section includes the following topics:
The Database Character Set Scanner enumerates all tables that need to be scanned into the CSM$TABLES table.
You can look up the number of tables (to get an estimate of how large CSM$TABLES can become) in the database by issuing the following SQL statement:
SELECT COUNT(*) FROM DBA_TABLES;
The Database Character Set Scanner stores statistical information for each column scanned into the CSM$COLUMNS table.
You can look up the number of character type columns (to get an estimate of how large CSM$COLUMNS can become) in the database by issuing the following SQL statement:
SELECT COUNT(*) FROM DBA_TAB_COLUMNS
WHERE DATA_TYPE IN ('CHAR', 'VARCHAR2', 'LONG', 'CLOB', 'VARRAY');
When exceptions are detected with cell data, the Database Character Set Scanner inserts individual exception information into the CSM$ERRORS table. This information then appears in the Individual Exception Report and facilitates identifying records to be modified if necessary.
If your database contains a lot of data that is signaled as Exceptional or Convertible (when the parameter CAPTURE=Y is set), then the CSM$ERRORS table can grow very large. You can prevent the CSM$ERRORS table from growing unnecessarily large by using the SUPPRESS parameter.
The SUPPRESS parameter applies to all tables. The Database Character Set Scanner suppresses inserting individual Exceptional information after the specified number of exceptions is inserted. Limiting the number of exceptions to be recorded may not be useful if the exceptions are spread over different tables.
This section describes how to improve performance when scanning the database.
If you plan to scan a relatively large database, for example, over 50GB, then you might want to consider using multiple scan processes. This shortens the duration of database scans by using hardware resources such as CPU and memory available on the machine. A guideline for determining the number of scan processes to use is to set the number equal to the CPU_COUNT initialization parameter.
The Database Character Set Scanner fetches multiple rows at a time when an array fetch is allowed. You can usually improve performance by letting the Database Character Set Scanner use a bigger array fetch buffer. Each process allocates its own fetch buffer.
When the Character Set Scanner is run without specifying the QUERY parameter, each SELECT operation created by CSSCAN will automatically include a /*+ROWID*/ hint. This is to enable faster access, so that all data retrieval will be performed using ROWID when performing table scans. When a QUERY parameter is supplied, the scanner assumes that the condition in the WHERE clause may already be optimized by other means, hence the ROWID hint will not be added to the QUERY clause.
To ensure optimal performance when using the QUERY parameter, careful tuning (for example, creating additional indexes) will be needed in the SELECT statements.
The Database Character Set Scanner inserts individual Exceptional and Convertible (when CAPTURE=Y) information into the CSM$ERRORS table. In general, insertion into the CSM$ERRORS table is more costly than data fetching. If your database has a lot of data that is signaled as Exceptional or Convertible, then the Database Character Set Scanner issues many insert statements, causing performance degradation. Oracle recommends setting a limit on the number of exception rows to be recorded using the SUPPRESS parameter.
All the character-based data in CHAR, VARCHAR2, LONG, CLOB, and VARRAY columns are stored in the database character set, which is specified with the CREATE DATABASE statement when the database is first created. However, in some configurations, it is possible to store data in a different character set from the database character set either intentionally or unintentionally. This happens most often when the NLS_LANG character set is the same as the database character set, because in such cases Oracle Database sends and receives data as is, without conversion or validation being guaranteed. It can also happen if one of the two character sets is a superset of the other, in which case many of the code points appear as if they were not converted. For example, if NLS_LANG is set to WE8ISO8859P1 and the database character set is WE8MSWIN1252, then all code points except the range 128-159 are preserved through the client/server conversion.
The same binary code point value can be used to represent different characters between the different character sets. Most European character sets share liberal use of the 8-bit range to encode native characters, so it is very possible for a cell to be reported as convertible but for the wrong reasons. When you set the FROMCHAR parameter, the assumption is that all character data is encoded in that character set, but the Database Character Set Scanner may not be able to accurately determine its validity.
For example, this can occur when the Database Character Set Scanner is used with the FROMCHAR parameter set to WE8MSWIN1252. This single-byte character set encodes a character in every available code point so that no matter what data is being scanned, the scanner always identifies a data cell as being available in the source character set.
If a database contains data that is not in the database character set, but it is encoded in another character set, then the Database Character Set Scanner can perform a scan if the FROMCHAR parameter specifies the encoded character set.
If a database contains data from more than one character set, then the Database Character Set Scanner cannot accurately test the effects of changing the database character set by a single scan. If the data can be divided into separate tables, one for each character set, then the Database Character Set Scanner can perform multiple table scans to verify the validity of the data.
For each scan, use a different value of the FROMCHAR parameter to tell the Database Character Set Scanner to treat all target columns in the table as if they were in the specified character set.
The CSALTER script is a DBA tool for special character set migration. Similar to the obsolete ALTER DATABASE CHARACTER SET SQL statement, CSALTER should be used only by the system administrator. System administrators must run the Database Character Set Scanner first to confirm that the proper conditions exist for running CSALTER. Also, the database must be backed up before running CSALTER.
To run the CSALTER script, start SQL*Plus and connect to the database whose character set is to be migrated. Note that the Database Character Set Scanner must be run before the CSALTER script. Then enter the following command:
sqlplus> @@CSALTER.PLB
The CSALTER script includes the following phases:
In the checking phase, the CSALTER script performs the following tasks:
It checks whether the user login is SYS. Only user SYS is allowed to run the script.
It checks whether a full database scan has been previously run within the last 7 days. If a full database scan has not been previously run, then the script stops and reports an error. It is the DBA's responsibility to ensure that no one updates the database between the times when the full database scans and the CSALTER script is run.
It checks whether CLOB columns in the data dictionary that were created by Oracle Database are changeless or convertible. Convertible CLOB columns occur when migrating from a single-byte character set to a multibyte character set. If there are any lossy cells found in CLOB columns in the data dictionary, then the script stops. The lossy CLOB columns may need to be specially handled; contact Oracle Support Services for more information.
Any table that belongs to the following schemas is considered to be part of the data dictionary:
SYSSYSTEMCTXSYSDIPDMSYSEXFSYSLBACSYSMDSYSORDDATAORDPLUGINSORDSYSSI_INFORMTN_SCHEMAXDBIt checks whether all CLOB columns in the Sample Schemas created by Oracle Database are changeless or convertible. Convertible CLOB columns occur when migrating from a single-byte character set to a multibyte character set. The tables that belong to the following schemas are part of the Sample Schemas:
HROESHPMIt checks whether the CLOB dataype is the only data type that contains convertible data in the data dictionary and Sample Schemas. It checks that all other users' tables have no convertible data for all data types including the CLOB data type. Because the CSALTER script is meant to be run only when the current database is a proper subset of the new database, all data should be changeless with the possible exception of the CLOB data. When migrating from a single-byte character set to a multibyte character set, user-created CLOB data requires conversion and must first be exported and deleted from the schema. The database must be rescanned in order to run the CSALTER script. Cells of all other data types that are reported to be convertible or subject to truncation must be corrected before the Database Character Set Scanner is rerun.
See Also:
"Migrating a Character Set Using the CSALTER Script" for more information about the CSALTER script and CLOB data
After the CSALTER script confirms that every CLOB in the data dictionary passes the checks described in "Checking Phase of the CSALTER Script", the CSALTER script performs the conversion. After all CLOB data in the data dictionary and the Sample Schemas have been updated, the script commits the change and saves the information in the CSM$TABLES view. After all CLOB data in the data dictionary have been updated, the CSALTER script updates the database metadata to the new character set. The entire migration process is then completed.
The CSALTER script is resumable. If the update of the database to the new character set fails at any time, then the DBA must shut down and restart the database and rerun the CSALTER script before doing anything else. Because the updated information is already saved in the CSM$TABLES view, the script will not update the CLOB data in the data dictionary tables twice. The process of migration is simply resumed to finish the update of the database to the new character set.
If the CSALTER script fails, then use the following method to resume the update:
From the SQL*Plus session where the CSALTER script was run, enter the following command immediately:
SHUTDOWN ABORT
Start up the database and open it, because CSALTER requires an open database.
STARTUP OPEN
Run the CSALTER script:
@@CSALTER.PLB
Shut down the database with either the IMMEDIATE or the NORMAL option.
Start up the database.
The Database Character Set Scanner uses the following views:
This view contains statistical information about columns that were scanned.
| Column Name | Data Type | NULL | Description |
|---|---|---|---|
OWNER_ID |
NUMBER |
NOT NULL |
User ID of the table owner |
OWNER_NAME |
VARCHAR2(30) |
NOT NULL |
User name of the table owner |
TABLE_ID |
NUMBER |
NOT NULL |
Object ID of the table |
TABLE_NAME |
VARCHAR2(30) |
NOT NULL |
Object name of the table |
COLUMN_ID |
NUMBER |
NOT NULL |
Column ID |
COLUMN_INTID |
NUMBER |
NOT NULL |
Internal column ID (for abstract data types) |
COLUMN_NAME |
VARCHAR2(30) |
NOT NULL |
Column name |
COLUMN_TYPE |
VARCHAR2(9) |
NOT NULL |
Column data type |
TOTAL_ROWS |
NUMBER |
NOT NULL |
Number of rows in this table |
NULL_ROWS |
NUMBER |
NOT NULL |
Number of NULL data cells |
CONV_ROWS |
NUMBER |
NOT NULL |
Number of data cells that need to be converted |
ERROR_ROWS |
NUMBER |
NOT NULL |
Number of data cells that have exceptions |
EXCEED_SIZE_ROWS |
NUMBER |
NOT NULL |
Number of data cells that have truncations |
DATA_LOSS_ROWS |
NUMBER |
- | Number of data cells that undergo lossy conversion |
MAX_POST_CONVERT_SIZE |
NUMBER |
- | Maximum post-conversion data size |
This view contains statistical information about constraints that were scanned.
| Column Name | Data Type | NULL | Description |
|---|---|---|---|
OWNER_ID |
NUMBER |
NOT NULL |
User ID of the constraint owner |
OWNER_NAME |
VARCHAR2(30) |
NOT NULL |
User name of the constraint owner |
CONSTRAINT_ID |
NUMBER |
NOT NULL |
Object ID of the constraint |
CONSTRAINT_NAME |
VARCHAR2(30) |
NOT NULL |
Object name of the constraint |
CONSTRAINT_TYPE# |
NUMBER |
NOT NULL |
Constraint type number |
CONSTRAINT_TYPE |
VARCHAR2(11) |
NOT NULL |
Constraint type name |
TABLE_ID |
NUMBER |
NOT NULL |
Object ID of the table |
TABLE_NAME |
VARCHAR2(30) |
NOT NULL |
Object name of the table |
CONSTRAINT_RID |
NUMBER |
NOT NULL |
Root constraint ID |
CONSTRAINT_LEVEL |
NUMBER |
NOT NULL |
Constraint level |
This view contains individual exception information for cell data and object definitions.
| Column Name | Data Type | NULL | Description |
|---|---|---|---|
OWNER_ID |
NUMBER |
NOT NULL |
User ID of the table owner |
OWNER_NAME |
VARCHAR2(30) |
NOT NULL |
User name of the table owner |
TABLE_ID |
NUMBER |
NOT NULL |
Object ID of the table |
TABLE_NAME |
VARCHAR2(30) |
- |
Object name of the table |
COLUMN_ID |
NUMBER |
- |
Column ID |
COLUMN_INTID |
NUMBER |
- |
Internal column ID (for abstract data types) |
COLUMN_NAME |
VARCHAR2(30) |
- |
Column name |
DATA_ROWID |
VARCHAR2(1000) |
- |
The rowid of the data |
COLUMN_TYPE |
VARCHAR2(9) |
- |
Column data type of object type |
ERROR_TYPE |
VARCHAR2(11) |
- |
Type of error encountered |
This view contains individual exception information for indexes.
| Column Name | Data Type | NULL | Description |
|---|---|---|---|
INDEX_OWNER_ID |
NUMBER |
NOT NULL |
User ID of the index owner |
INDEX_OWNER_NAME |
VARCHAR2(30) |
NOT NULL |
User name of the index owner |
INDEX_ID |
NUMBER |
NOT NULL |
Object ID of the index |
INDEX_NAME |
VARCHAR2(30) |
- |
Object name of the index |
INDEX_STATUS# |
NUMBER |
- |
Status number of the index |
INDEX_STATUS |
VARCHAR2(8) |
- |
Status of the index |
TABLE_OWNER_ID |
NUMBER |
- |
User ID of the table owner |
TABLE_OWNER_NAME |
VARCHAR2(30) |
- |
User name of the table owner |
TABLE_ID |
NUMBER |
- |
Object ID of the table |
TABLE_NAME |
VARCHAR2(30) |
- |
Object name of the table |
COLUMN_ID |
NUMBER |
- |
Column ID |
COLUMN_INTID |
NUMBER |
- |
Internal column ID (for abstract data types) |
COLUMN_NAME |
VARCHAR2(30) |
- |
Column name |
This view contains information about database tables to be scanned. The Database Character Set Scanner enumerates all tables to be scanned into this view.
| Column Name | Data Type | NULL | Description |
|---|---|---|---|
OWNER_ID |
NUMBER |
NOT NULL |
User ID of the table owner |
OWNER_NAME |
VARCHAR2(30) |
NOT NULL |
User name of the table owner |
TABLE_ID |
NUMBER |
- |
Object ID of the table |
TABLE_NAME |
VARCHAR2(30) |
- |
Object name of the table |
MIN_ROWID |
VARCHAR2(18) |
- |
Minimum rowid of the split range of the table |
MAX_ROWID |
VARCHAR2(18) |
- |
Maximum rowid of the split range of the table |
BLOCKS |
NUMBER |
- |
Number of blocks in the split range |
SCAN_COLUMNS |
NUMBER |
- |
Number of columns to be scanned |
SCAN_ROWS |
NUMBER |
- |
Number of rows to be scanned |
SCAN_START |
VARCHAR2(8) |
- |
Time table scan started |
SCAN_END |
VARCHAR2(8) |
- |
Time table scan completed |
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