checkBufferPool
checkBufferPool is a custom policy check that checks that the Buffer Pool specified in the tablespace matches the default Buffer Pool for the database.
Learn how to create and customize the checkBufferPool Liquibase Custom Policy Check using a Python script.
This example utilizes DB2 on zOS. You can use this check as it is or customize it further to fit your needs in your SQL database.
For a conceptual overview of this feature, see Liquibase Pro Custom Policy Checks.
Before you begin
Scope | Database |
| DB2 on zOS |
Liquibase Prerequisites
Liquibase 4.29.0+
Configure a valid Liquibase Pro license key
create a Checks settings file
Ensure the Liquibase Checks extension is installed. In Liquibase 4.31.0+, it is already installed in the
/liquibase/internal/lib
directory, so no action is needed.If the checks JAR is not installed, download
liquibase-checks-<version>.jar
and put it in theliquibase/lib
directory.Maven users only:
Add this dependency to your
pom.xml
file:
<dependency> <groupId>org.liquibase.ext</groupId> <artifactId>liquibase-checks</artifactId> <version>2.0.0</version> </dependency>
Java Development Kit 17+ (available for Open JDK and Oracle JDK)
Linux, macOS, or Windows operating system
checkBufferPool
These steps describe how to create the Custom Policy Check. It does not exist by default in Liquibase Pro.
Add this code to your Checks Settings file:
checkBufferPool Python Script
# # #
# # # This script checks that the Buffer Pool specified in the tablespace
# # # matches the
default Buffer Pool
for the Database.
# # #
# # #
# # # This script throws the following errors:
# # # 1) Multiple CREATE TABLESPACE statements found in changeset.Only one CREATE TABLESPACE allowed per changeset.
# # # 2) Default Buffer Pool Not Found
for Database {
database_name
}.
# # # 3) Multiple BUFFER POOL statements found in CREATE TABLESPACE statement.Only one Buffer Pool can be specified.
# # # 4) Buffer Pool Not Found in CREATE TABLESPACE script.
# # # 5) CREATE TABLESPACE Buffer Pool(buffer_name) must match the
default Buffer Pool(default_buffer_pool) for the database(database_name).
# # #
# # # Sample Tablespace:
# # #
# # # CREATE TABLESPACE SBA01003
# # # IN DBA0001
# # # USING STOGROUP SYSPOOL1
# # # PRIQTY 720 SECQTY 720
# # # ERASE NO
# # # FREEPAGE 5 PCTFREE 15 FOR UPDATE 0
# # # GBPCACHE CHANGED
# # # TRACKMOD YES
# # # MAXPARTITIONS 20
# # # LOGGED
# # # DSSIZE 8 G
# # # SEGSIZE 32
# # # BUFFERPOOL BP0
# # # LOCKSIZE ANY
# # # LOCKMAX SYSTEM....
# # #
# # # Query to find
default Buffer Pool:
# # #
# # # SELECT BPOOL FROM SYSIBM.SYSDATABASE WHERE NAME = 'DBA0001';
# # #
# # # Helpers come from Liquibase
# # #
import liquibase_utilities
import re
import sys
# # #
# # # main
# # #
# # #
# # # Retrieve log handler
# # # Ex.liquibase_logger.info(message)
# # #
liquibase_logger = liquibase_utilities.get_logger()
# # #
# # # Retrieve status handler
# # #
liquibase_status = liquibase_utilities.get_status()
# # #
# # # Define regex patterns
for a Tablespace 's DatabaseName and BufferPool
# # #
regex_pattern_database = f "(?is)CREATE\s+TABLESPACE\s+\w+\s+IN\s+(\w+)"
regex_pattern_bufferpool = f "(?is)BUFFERPOOL\s+(\S+)"
# # #
# # # Retrieve all changes in changeset
# # #
changes = liquibase_utilities.get_changeset().getChanges()
# # #
# # # Loop through all changes
# # #
for change in changes:
# # #
# # # LoadData change types are not currently supported
# # #
if "loaddatachange" in change.getClass().getSimpleName().lower():
continue
# # #
# # # Split sql into a list of strings to remove whitespace
# # #
raw_sql = liquibase_utilities.generate_sql(change)
# # #
# # # Look
for database regex in SQL
# # #
database_list = re.findall(regex_pattern_database, raw_sql)
if len(database_list) > 1:
liquibase_status.fired = True
status_message = f "Multiple CREATE TABLESPACE statements found in changeset. Only one CREATE TABLESPACE allowed per changeset."
liquibase_status.message = status_message
sys.exit(1)
break
else:
database_name = ''.join(database_list)
# # #
# # # End check
if script does not contain regex pattern
# # #
if database_name is None or database_name == '':
break
else:
# # # print(f "Database Name: {database_name}")
# # #
# # # Execute query to get the
default buffer pool
for the database
# # #
sql_query = f "SELECT BPOOL FROM SYSIBM.SYSDATABASE WHERE NAME = '{database_name}'"
default_buffer_pool_list = liquibase_utilities.query_for_list(sql_query, None, ";")
if len(default_buffer_pool_list) == 0:
# # # print(f "Default Buffer Pool Not Found for Database {database_name}")
liquibase_status.fired = True
status_message = f "Default Buffer Pool Not Found for Database {database_name}."
liquibase_status.message = status_message
sys.exit(1)
break
else:
default_buffer_pool = default_buffer_pool_list[0]["BPOOL"].strip()
# # # print(f "Default Buffer Pool: {default_buffer_pool}")
# # #
# # # Look
for bufferpool regex in SQL
# # #
buffer_pool_list = re.findall(regex_pattern_bufferpool, raw_sql)
if len(buffer_pool_list) > 1:
liquibase_status.fired = True
status_message = f "Multiple BUFFER POOL statements found in CREATE TABLESPACE statement. Only one Buffer Pool can be specified."
liquibase_status.message = status_message
sys.exit(1)
break
else:
buffer_pool = ''.join(buffer_pool_list)
if buffer_pool is None or buffer_pool == '':
# # # print(f "Buffer Pool Not Found in script {buffer_pool}")
liquibase_status.fired = True
status_message = f "Buffer Pool Not Found in CREATE TABLESPACE script."
liquibase_status.message = status_message
sys.exit(1)
break
else:
# # # print(f "Buffer Pool in script: {buffer_pool}")
# # #
# # # Check that the buffer pool values match
# # #
if buffer_pool != default_buffer_pool:
liquibase_status.fired = True
status_message = str(liquibase_utilities.get_script_message()).replace("__BUFFER_POOL__", f "{buffer_pool}")
status_message = status_message.replace("__DEFAULT_BUFFER_POOL__", f "{default_buffer_pool}")
status_message = status_message.replace("__DATABASE_NAME__", f "{database_name}")
liquibase_status.message = status_message
sys.exit(1)
break
# # #
# # # Default
return code
# # #
False
Initiate the customization process
In the CLI, run this command:
liquibase checks customize --check-name=CustomCheckTemplate
The CLI prompts you to finish configuring your file. A message displays:
This check cannot be customized directly because one or more fields does not have a default value.
Liquibase will then create a copy of CustomCheckTemplate
and initiate the customization workflow.
Give your check a short name so you can easily identify what Python script it is associated with
You may use up to 64 alpha-numeric characters only.
In this example we will name the check:
checkBufferPool
Set the Severity to return a code of 0-4 when triggered.
These severity codes allow you to determine if the job moves forward or stops when this check triggers.
Learn more here: Use Policy Checks in Automation: Severity and Exit Code
options: 'INFO'=0
, 'MINOR'=1
, 'MAJOR'=2
, 'CRITICAL'=3
, 'BLOCKER'=4
Set SCRIPT_DESCRIPTION
In this example, we will set the description to:
This script checks that the Buffer Pool specified in the tablespace matches the default Buffer Pool for the database.
Set the SCRIPT_SCOPE
In this example, we will set the scope to:
changelog
: for example, if your check looks for syntax patterns or attributes in your Liquibase Changelog (the changes you author in your repository). With this value, the check runs once per changeset.
Set the SCRIPT_MESSAGE
This message will display when the check is triggered. In this example we will use:
CREATE TABLESPACE Buffer Pool (__BUFFER_POOL__) must match the default Buffer Pool (__DEFAULT_BUFFER_POOL__) for the database (__DATABASE_NAME__).
Set the SCRIPT_PATH
This is the relative path where your script is stored in relation to the changelog specified in --changelog-file
, whether it is stored locally or in a repository.
In this example, we will set the path to:
scripts/collection-camel-case.py
This check does not require a SCRIPT_ARGUMENT, so leave this blank.
Set the REQUIRES_SNAPSHOT
If your script scope is changelog
, set whether the check requires a database snapshot. Specify true
if your check needs to inspect database objects.
If your script scope is database
, Liquibase always takes a snapshot, so this prompt does not appear.
Note: The larger your database, the more performance impact a snapshot causes. If you cannot run a snapshot due to memory limitations, see Memory Limits of Inspecting Large Schemas.