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HCL OneDB 2.0.1
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HCL OneDB™
2.0.1
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HCL OneDB™
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Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
System administration
These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning
HCL OneDB™
database servers.
Performance Guide
The
HCL OneDB™ Performance Guide
describes how to configure and operate your
HCL OneDB™
database server to improve overall system throughput and to improve the performance of SQL queries.
Improving individual query performance
You can test, monitor, and improve queries.
Administering
In addition to administering the database server, you can tune performance, replicate data, and archive data.
System administration
These topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning
HCL OneDB™
database servers.
Administrator's Guide
The
HCL OneDB™ Administrator's Guide
provides the information required to administer
HCL OneDB™
.
Administrator's Reference
The
HCL OneDB™ Administrator's Reference
includes comprehensive descriptions of
HCL OneDB™
configuration parameters, the system-monitoring interface (SMI) tables in the sysmaster database, the syntax of database server utilities such as
onmode
and
onstat
, logical-log records, disk structures, event alarms, and unnumbered error messages.
DB-Access User's Guide
This publication describes how to use the
DB-Access
utility to access, modify, and retrieve information from
HCL® OneDB®
database servers.
Performance Guide
The
HCL OneDB™ Performance Guide
describes how to configure and operate your
HCL OneDB™
database server to improve overall system throughput and to improve the performance of SQL queries.
Performance basics
Performance measurement and tuning issues and methods are relevant to daily database server administration and query execution.
Performance monitoring and the tools you use
You can use performance monitoring tools to create a performance history, to monitor database resources at scheduled times, or to monitor ongoing transaction or query performance.
Effect of configuration on CPU utilization
The combination of operating-system and
HCL OneDB™
configuration parameters can affect CPU utilization. You can change the settings of the
HCL OneDB™
configuration parameters that directly affect CPU utilization, and you can adjust the settings for different types of workloads.
Effect of configuration on memory utilization
The combination of operating-system and
HCL OneDB™
configuration parameters can affect memory utilization.
Effect of configuration on I/O activity
The configuration of your database server affects I/O activity.
Table performance considerations
Some performance issues are associated with unfragmented tables and table fragments.
Indexes and index performance considerations
HCL OneDB™
provides several types of indexes. Some performance issues are associated with indexes.
Locking
The database server uses locks, which can affect concurrency and performance. You can monitor and administer locks.
Fragmentation guidelines
One of the most frequent causes of poor performance in relational database systems is contention for data that resides on a single I/O device. Proper fragmentation of high-use tables can significantly reduce I/O contention. These topics discuss the performance considerations that are involved when you use table fragmentation.
Queries and the query optimizer
These topics describe query plans, explain how the database server manages query optimization, and discuss factors that you can use to influence the query plan. These topics also describe performance considerations for SPL routines, the UDR cache, and triggers.
Optimizer directives
Optimizer directives
are comments that tell the query optimizer how to execute a query. You can use optimizer directives to improve query performance.
Parallel database query (PDQ)
You can manage how the database server performs PDQ and you can monitor the resources that the database server uses for PDQ.
Improving individual query performance
You can test, monitor, and improve queries.
Test queries using a dedicated test system
You can test a query on a system that does not interfere with production database servers. However, you must be careful, because testing queries on a separate system might distort your tuning decisions.
Display the query plan
Before you change a query, display its query plan to determine the kind and amount of resources that the query requires. The query plan shows what parallel scans are used, the maximum number of threads required, and the indexes used.
Improve filter selectivity
You can control the amount of information that a query evaluates. The greater the precision with which you specify the desired rows, the greater the likelihood that your queries will complete quickly.
Automatic statistics updating
The database server updates statistics automatically according to a predefined schedule and a set of expiration policies. The Auto Update Statistics (AUS) maintenance system identifies tables and indexes that require new optimizer statistics and runs the appropriate UPDATE STATISTICS statements to optimize query performance.
Update statistics when they are not generated automatically
The UPDATE STATISTICS statement updates the statistics in the system catalog tables that the optimizer uses to determine the lowest-cost query plan.
Improve performance by adding or removing indexes
You can often improve the performance of a query by adding or, in some cases, removing indexes. You can also enable the optimizer to automatically fetch a set of keys from an index buffer.
Optimizer estimates of distributed queries
The optimizer assumes that access to a row from a remote database takes longer than access to a row in a local database. The optimizer estimates include the cost of retrieving the row from disk and transmitting it across the network.
Improve sequential scans
You can improve the performance of sequential read operations on large tables by eliminating repeated sequential scans.
Enable view folding to improve query performance
You can significantly improve the performance of a query that involves a view by enabling view folding.
Reduce the join and sort operations
After you understand what the query is doing, you can look for ways to obtain the same output with less effort.
Optimize user-response time for queries
You can influence the amount of time that
OneDB
takes to optimize a query and to return rows to a user.
Optimize queries for user-defined data types
Queries that access user-defined data types (UDTs) can take advantage of the same performance features that built-in data types use.
Optimize queries with the SQL statement cache
Before the database server runs an
SQL
statement, it must first parse and optimize the statement. Optimizing statements can be time consuming, depending on the size of the
SQL
statement.
Monitor sessions and threads
You can monitor the number of active sessions and threads and the amount of resources that they are using. Monitoring sessions and threads is important for sessions that perform queries as well as sessions that perform inserts, updates, and deletes.
Monitor transactions
You can monitor transactions to track open transactions and the locks that those transactions hold. You can use several
onstat
utility options to view transaction, lock, and session statistics.
The onperf utility on UNIX
The
onperf
utility is a windowing environment that you can use to monitor the database server performance. The
onperf
utility monitors the database server running on the UNIX™ operating system.
Appendix
OneDB Explore
OneDB Explore
is a modern web console for visualizing, monitoring, and managing your
OneDB
server instances. It is purpose built for ease-of-use, scaling out, and optimizing DevOps needs. It provides critical performance management capabilities, monitoring how key performance metrics are changing over time and tracking how efficiently
OneDB
is running your workload even when you’ve stepped away from your screen. Its monitoring system feeds directly into a customizable alerting system so you can be immediately alerted via email, Twilio, or PagerDuty whenever an issue occurs on one of your
OneDB
database server instances.
OneDB Explore
is designed to be scalable to efficiently manage and monitor as many OneDB database server instances as you need. Moreover, it's a tool that can be shared by the DBAs, the app developers, the ops engineers, and management and accessed from any desktop, laptop, or mobile device. OneDB Explore is the centralized hub for graphical monitoring, alerting, and administration of your
OneDB
database servers.
Backup and Restore Guide
The
HCL OneDB™ Backup and Restore Guide
describes how to use the
HCL® OneDB®
ON-Bar
utility to back up and restore database server data.
This will enable you to recover your databases after data is lost or becomes corrupted due to hardware or software failure or accident.
Enterprise Replication
The
HCL OneDB™
Enterprise Replication Guide
describes the concepts of data replication using
HCL® OneDB® Enterprise Replication
, including how to design your replication system, as well as administer and manage data replication throughout your enterprise.
Improving individual query performance
You can test, monitor, and improve queries.
Test queries using a dedicated test system
You can test a query on a system that does not interfere with production database servers. However, you must be careful, because testing queries on a separate system might distort your tuning decisions.
Display the query plan
Before you change a query, display its query plan to determine the kind and amount of resources that the query requires. The query plan shows what parallel scans are used, the maximum number of threads required, and the indexes used.
Improve filter selectivity
You can control the amount of information that a query evaluates. The greater the precision with which you specify the desired rows, the greater the likelihood that your queries will complete quickly.
Automatic statistics updating
The database server updates statistics automatically according to a predefined schedule and a set of expiration policies. The Auto Update Statistics (AUS) maintenance system identifies tables and indexes that require new optimizer statistics and runs the appropriate UPDATE STATISTICS statements to optimize query performance.
Update statistics when they are not generated automatically
The UPDATE STATISTICS statement updates the statistics in the system catalog tables that the optimizer uses to determine the lowest-cost query plan.
Improve performance by adding or removing indexes
You can often improve the performance of a query by adding or, in some cases, removing indexes. You can also enable the optimizer to automatically fetch a set of keys from an index buffer.
Optimizer estimates of distributed queries
The optimizer assumes that access to a row from a remote database takes longer than access to a row in a local database. The optimizer estimates include the cost of retrieving the row from disk and transmitting it across the network.
Improve sequential scans
You can improve the performance of sequential read operations on large tables by eliminating repeated sequential scans.
Enable view folding to improve query performance
You can significantly improve the performance of a query that involves a view by enabling view folding.
Reduce the join and sort operations
After you understand what the query is doing, you can look for ways to obtain the same output with less effort.
Optimize user-response time for queries
You can influence the amount of time that
OneDB
takes to optimize a query and to return rows to a user.
Optimize queries for user-defined data types
Queries that access user-defined data types (UDTs) can take advantage of the same performance features that built-in data types use.
Optimize queries with the SQL statement cache
Before the database server runs an
SQL
statement, it must first parse and optimize the statement. Optimizing statements can be time consuming, depending on the size of the
SQL
statement.
Monitor sessions and threads
You can monitor the number of active sessions and threads and the amount of resources that they are using. Monitoring sessions and threads is important for sessions that perform queries as well as sessions that perform inserts, updates, and deletes.
Monitor transactions
You can monitor transactions to track open transactions and the locks that those transactions hold. You can use several
onstat
utility options to view transaction, lock, and session statistics.
Related information
Tune the new version for performance and adjust queries
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