This command changes the update characteristics of an index.
For execution, the command needs to be prefixed with db2ts at
the command line.
Authorization
The
privileges held by the authorization ID of the statement must include
the SYSTS_MGR role and at least one of the following authorities:
- DBADM authority
- ALTERIN privilege on the base schema
- CONTROL or ALTER privilege on the base table on which the text
search index is defined
To change an existing schedule, the authorization ID must be
the same as the index creator or must have DBADM authority.
Required connection
Database
Command syntax
>>-ALTER INDEX--index-name--FOR TEXT---------------------------->
>--| update characteristics |--| options |---------------------->
>--| connection options |--------------------------------------><
update characteristics
|--+--------------------------------------------+--------------->
'-UPDATE FREQUENCY--+-NONE-----------------+-'
'-| update frequency |-'
>--| incremental update characteristics |-----------------------|
update frequency
|--D-(-+-*------------+-)--H-(-+-*------------+-)--------------->
| .-,--------. | | .-,--------. |
| V | | | V | |
'---integer1-+-' '---integer2-+-'
.-,--------.
V |
>--M-(---integer3-+-)-------------------------------------------|
incremental update characteristics
|--+----------------------------+-------------------------------|
'-UPDATE MINIMUM--minchanges-'
options
|--+----------------------------------+-------------------------|
+-| index configuration options |-+
'-| activation options |-----------'
index configuration options
|--+-------------------------------------------+----------------|
'-INDEX CONFIGURATION--(-| option-value |-)-'
option-value
|--+----------------------------------------------+-------------|
+-UPDATEAUTOCOMMIT--+-+--------------------+-+-+
| | '-commitcount_number-' | |
| '-+------------+---------' |
| '-commitsize-' |
+-COMMITTYPE--committype-----------------------+
'-COMMITCYCLES--commitcycles-------------------'
activation options
|--+-----------------------------------+------------------------|
SET--+-ACTIVE---+--+------------+---'
'-INACTIVE-' '-UNILATERAL-'
connection options
|--+----------------------------------------------------------------+--|
'-CONNECT TO--database-name--+---------------------------------+-'
'-USER--username--USING--password-'
Command parameters
- ALTER INDEX index-name
- The schema and name of the index as specified in the CREATE
INDEX command. It uniquely identifies the text search index
in a database.
- UPDATE FREQUENCY
- Specifies the frequency with which index updates are made. The
index will be updated, if the number of changes is at least the value
set for UPDATE MINIMUM. The update frequency NONE indicates
that no further index updates will be made. This can be useful for
a text column in a table with data that will not change. It is also
useful when the user intends to manually update the index (using the UPDATE
INDEX command). Automatic updates can only be done if the START
FOR TEXT command has been run and the DB2® Text Search instance services are running.
The
default frequency value is taken from the view SYSIBMTS.TSDEFAULTS,
where DEFAULTNAME='UPDATEFREQUENCY'.
- NONE
- No automatic updates will be applied to the text index. Any further
index update will have to be started manually.
- D
- The day(s) of the week when the index is updated.
- *
- Every day of the week.
- integer1
- Specific days of the week, from Sunday to Saturday: 0 to 6
- H
- The hour(s) of the specified day(s) when the index is updated.
- *
- Every hour of the day.
- integer2
- Specific hours of the day, from midnight to 11 pm: 0 to 23
- M
- The minute(s) of the specified hour(s) when the index is updated.
- integer3
- Specified as top of the hour (0), or in multiples of 5 minute
increments after the hour: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50
or 55
If you do not specify the UPDATE FREQUENCY option,
the frequency settings are left unchanged.
- UPDATE MINIMUM minchanges
- Specifies the minimum number of changes to text documents that
must occur before the index is incrementally updated. Multiple changes
to the same text document are treated as separate changes. If you
do not specify the UPDATE MINIMUM option, the setting
is left unchanged.
- INDEX CONFIGURATION (option-value)
- This is an optional input argument of type VARCHAR(32K) that allows
altering text index configuration settings. The following option is
supported:
Table 1. Specifications for option-valueOption |
Value |
Data type |
Description |
SERIALUPDATE |
updatemode |
Integer |
Specifies whether the update processing for
a partitioned text search index should be run in parallel or in serial
mode. In parallel mode the execution is distributed to the database
partitions and executes independently on each node. In serial mode
the execution is run without distribution and stops when a failure
is encountered. Serial mode execution usually takes longer but requires
significantly less resources. - 0 = parallel mode
- 1 = serial mode
|
UPDATEAUTOCOMMIT |
commitcount_number |
- |
- Specifies an integer option for the number of index updates after
which a commit is executed to preserve the previous work automatically
for either initial or incremental updates.
- For initial updates, the index update will process batches of
documents from a base table after the trigger to capture data updates
is activated. After the amount of documents updated reaches the COMMITCOUNT number,
the server will do an interim commit. Log entries generated by unprocessed
documents will be removed from the staging table. Using the UPDATEAUTOCOMMIT option
for an initial text index update will lead to a significant increase
of execution time.
- For incremental updates, log entries which have been processed
will be removed correspondingly from staging table with each interim
commit. COMMITCOUNT counts the number of documents
updated, not the number of staging table entries.
Starting in DB2 Version 10.1 Fix Pack 3 and later fix packs,
this string specifies the number of rows or number of hours after
which a commit is run to automatically preserve the previous work
for either initial or incremental updates.
If you specify the
number of rows: - After the number of documents that are updated reaches the COMMITCOUNT
number, the server applies a commit. COMMITCOUNT counts the number
of documents that are updated by using the primary key, not the number
of staging table entries.
If you specify the number of hours: - The text index is committed after the specified number of hours
is reached. The maximum number of hours is 24.
For initial updates, the index update processes batches
of documents from the base table. After the commitsize value
is reached, update processing completes a COMMIT operation and the
last processed key is saved in the staging table with the operational
identifier '4'. Use this key to restart update processing either
after a failure or after the number of specified commitcycles are
completed. If you specify a commitcycles , the
update mode is modified to incremental to initiate capturing changes
by using the LOGTYPE BASIC option
to create triggers on the text table. However, until the initial update
is complete, log entries that are generated by documents that have
not been processed in a previous cycle are removed from the staging
table.
Using the UPDATEAUTOCOMMIT option
for an initial text index update leads to a significant increase of
execution time.
For incremental updates, log entries that are
processed are removed correspondingly from the staging table with
each interim commit.
|
COMMITTYPE |
committype |
String |
Starting in DB2 Version 10.1 Fix Pack 3 and
later fix packs, specifies rows or hours for the UPDATEAUTOCOMMIT index
configuration option. The default is rows.
|
COMMITCYCLES |
commitcycles |
Integer |
Starting in DB2 Version 10.1 Fix Pack 3 and
later fix packs, specifies the number of commit cycles. The default
is 0 for unlimited cycles.
If cycles are not explicitly specified,
the update operation uses as many cycles as required based on the
batch size that is specified with the UPDATEAUTOCOMMIT option
to finish the update processing.
You can use this option with
the UPDATEAUTOCOMMIT setting with a committype.
|
- activation options
- Starting with Version 9.7 Fix Pack 3 and later fix packs, this
input argument of type integer sets the status of a text index.
- ACTIVE
- Sets the text index status to active
- INACTIVE
- Sets the text index status to inactive
- UNILATERAL
- Specifies a unilateral change which only affects the status of DB2 Text Search indexes. If this
argument is specified, only the status of a DB2 Text Search index is changed to active or
inactive. Without the UNILATERAL argument, the activation
status of the DB2 Text Search
and DB2 Net Search Extender
indexes is jointly switched so that only one of the text indexes is
active.
- CONNECT TO database-name
- This clause specifies the database to which a connection will
be established. The database must be on the local system. If specified,
this clause takes precedence over the environment variable DB2DBDFT.
This clause can be omitted if the following are all true:
- The DB2DBDFT environment variable is set to a valid database name.
- The user running the command has the required authorization to
connect to the database server.
- USER username USING password
- This clause specifies the username and password that will be used
to establish the connection.
Usage notes
All limits and naming conventions,
that apply to DB2 database objects
and queries, also apply to DB2 Text
Search features and queries. DB2 Text
Search related identifiers must conform to the DB2 naming conventions. In addition, there are
some additional restrictions. For example, these identifiers can only
be of the form:
[A-Za-z][A-Za-z0-9@#$_]*
or
"[A-Za-z ][A-Za-z0-9@#$_ ]*"
Note that multiple commands cannot be executed concurrently
on a text search index if they may conflict. If this command is issued
while a conflicting command is running, an error will occur and the
command will fail, after which you can try to run the command again.
Some of the conflicting commands are:
- ALTER INDEX
- CLEAR EVENTS FOR INDEX
- DROP INDEX
- UPDATE INDEX
- DISABLE DATABASE FOR TEXT
Changes to the database: Updates the DB2 Text Search catalog information.
The
result of activating indexes depends on the original index status.
The following table describes the results.
Table 2. Status changes
without invalid index: Initial DB2 Text
Search or Net Search Extender Status |
Request Active |
Request Active Unilateral |
Request Inactive |
Request Inactive Unilateral |
Active / Inactive |
No change |
No change |
Inactive / Active |
Inactive / Inactive |
Inactive / Active |
Active / Inactive |
Error |
No change |
No change |
Inactive / Inactive |
Active / Inactive |
Active / Inactive |
Inactive / Active |
No change |
SQL20427N and
CIE0379E error
messages are returned for active index conflicts.
You can specify the UPDATEAUTOCOMMIT index
configuration option without type and cycles for compatibility with
an earlier version. It is associated by default with the COMMITTYPE rows option
and unrestricted cycles.
You can specify
the UPDATEAUTOCOMMIT, COMMITTYPE and COMMITSIZE
index configuration options for an UPDATE INDEX operation to override
the configured values. Values that you submit for a specific update
operation are applied only once and not persisted.