Connection parameters that affect performance

batch

The default, “on,” allows command batches to a replicate database.

Default: on

db_packet_size

The maximum size of a network packet. During database communication, the network packet value must be within the range accepted by the database.

Maximum: 16384 bytes

Default: 512-byte network packet for all Adaptive Server databases

disk_affinity

Specifies an allocation hint for assigning the next partition. Enter the logical name of the partition to which the next segment should be allocated when the current partition is full. Values are “partition_name” and “off.”

Default: off

dist_sqt_max_cache_size

The maximum Stable Queue Transaction (SQT) cache size for the inbound queue in bytes. The default, 0, means the current setting of the sqt_max_cache_size parameter is used as the maximum cache size for the connection.

Default: 0

For 32-bit Replication Server:

• Minimum – 0

• Maximum – 2,147,483,647

For 64-bit Replication Server:

• Minimum – 0

• Maximum – 2,251,799,813,685,247

dsi_cmd_batch_size

The maximum number of bytes that Replication Server places into a command batch.

Default: 8192 bytes

dsi_cmd_prefetch

Allows DSI to pre-build the next batch of commands while waiting for the response from data server, and therefore improves DSI efficiency. If you also tune your data server to enhance performance, it is likely that you will gain an additional performance increase when you use this feature.

Default: on

When you set dsi_compile_enable to ‘on’, Replication Server ignores what you set for dsi_cmd_prefetch.

License: Separately licensed under the Advanced Services Option. See “Replication Server – Advanced Services Option”.

dsi_commit_check_locks_intrvl

The number of milliseconds (ms) the DSI executor thread waits between executions of the rs_dsi_check_thread_lock function string. Used with parallel DSI. See “Using parallel DSI threads”.

Default: 1000 ms (1 second)

Minimum: 0

Maximum: 86,400,000 ms (24 hours)

dsi_commit_check_locks_max

The maximum number of times the DSI executor thread executes the rs_dsi_check_thread_lock function string before rolling back and retrying a transaction. Used with parallel DSI. See “Using parallel DSI threads”.

Default: 400

Minimum: 1

Maximum: 1,000,000

dsi_commit_control

Specifies whether commit control processing is handled internally by Replication Server using internal tables (on) or externally using the rs_threads system table (off). Used with parallel DSI. See “Using parallel DSI threads”.

Default: on

dsi_isolation_level

Specifies the isolation level for transactions. ANSI standard and Adaptive Server supported values are:

• 0 – ensures that data written by one transaction represents the actual data.

• 1 – prevents dirty reads and ensures that data written by one transaction represents the actual data.

• 2 – prevents nonrepeatable reads and dirty reads, and ensures that data written by one transaction represents the actual data.

• 3 – prevents phantom rows, nonrepeatable reads, and dirty reads, and ensures that data written by one transaction represents the actual data.

Through the use of custom function strings, Replication Server can support any isolation level the replicate data server may use. Support is not limited to the ANSI standard only.

Default: the current transaction isolation level for the target data server

dsi_large_xact_size

The number of commands allowed in a transaction before the transaction is considered to be large.

Default: 100

Minimum: 4

Maximum: 2,147,483,647

dsi_max_cmds_in_batch

Defines maximum number of source commands for which output commands can be batched.

Range: 1 – 1000

Default: 100

dsi_max_xacts_in_group

Specifies the maximum number of transactions in a group. Larger numbers may reduce commit processing at the replicate database, and thereby improve throughput. Range of values: 1 – 1000.

See “Specifying the number of transactions in a group”.

Default: 20

dsi_num_large_xact_threads

The number of parallel DSI threads to be reserved for use with large transactions. The maximum value is one less than the value of dsi_num_threads.

Default: 0

dsi_num_threads

The number of parallel DSI threads to be used. The maximum value is 255.

Default: 1

dsi_partitioning_rule

Specifies the partitioning rules (one or more) the DSI uses to partition transactions among available parallel DSI threads. Values are origin, origin_sessid, none, time, user, and name. See also “Partitioning rules: reducing contention and increasing parallelism”.

Default: none

dsi_serialization_method

Specifies the method used to determine when a transaction can start, while still maintaining consistency. In all cases, commit order is preserved.

These methods are ordered from most to least amount of parallelism. Greater parallelism can lead to more contention between parallel transactions as they are applied to the replicate database. To reduce contention, use the dsi_partition_rule option.

• no_wait – specifies that a transaction can start as soon as it is ready—without regard to the state of other transactions.

  You can only set dsi_serialization_method to no_wait if dsi_commit_control is set to “on”.

• wait_for_start – specifies that a transaction can start as soon as the transaction scheduled to commit immediately before it has started.

• wait_for_commit (default) – specifies that a transaction cannot start until the transaction scheduled to commit immediately preceding it is ready to commit.

• wait_after_commit – specifies that a transaction cannot start until the transaction scheduled to commit immediately preceding it has committed completely.

These options are retained only for backward compatibility with older versions of Replication Server:

• none – same as wait_for_start.

• single_transaction_per_origin – same as wait_for_start with dsi_partitioning_rule set to origin.

Default: wait_for_commit

dsi_sqt_max_cache_size

Maximum SQT (Stable Queue Transaction) interface cache size for the outbound queue in bytes. The default, 0, means the current setting of the sqt_max_cache_size parameter is used as the maximum cache size for the connection.

Default: 0

For 32-bit Replication Server:

• Minimum – 0

• Maximum – 2,147,483,647

For 64-bit Replication Server:

• Minimum – 0

• Maximum – 2,251,799,813,685,247

dsi_xact_group_size

The maximum number of bytes, including stable queue overhead, to place into one grouped transaction. A grouped transaction is a set of transactions that the DSI applies as a single transaction. –1 means no grouping.

Sybase recommends that you set dsi_xact_group_size to the maximum value and use dsi_max_xacts_in_group to control the number of transactions in a group.

Default: 65,536 bytes

Maximum: 2,147,483,647

exec_cmds_per_timeslice

Specifies the number of LTL commands an LTI or RepAgent executor thread can process before yielding the CPU. By increasing this value, you allow the RepAgent executor thread to control CPU resources for longer periods of time, which may improve throughput from RepAgent to Replication Server.

Set this parameter at the connection level using alter connection.

See “Controlling the number of commands the RepAgent executor can process”.

Default: 2,147,483,647

Minimum: 1

Maximum: 2,147,483,647

exec_nrm_request_limit

Specifies the amount of memory available for messages from a primary database waiting to be normalized.

Set nrm_thread to ‘on’ with configure replication server before you use exec_nrm_request_limit.

Minimum: 16,384 bytes

Maximum: 2,147,483,647 bytes

Default for:

• 32-bit – 1,048,576 bytes (1MB)

• 64-bit – 8,388,608 bytes (8MB)

After you change the configuration for exec_nrm_request_limit, suspend and resume the Replication Agent.

License: Separately licensed under the Advanced Services Option. See “Replication Server – Advanced Services Option”.

exec_sqm_write_request_limit

Specifies the amount of memory available for messages waiting to be written to an inbound queue.

Default: 1MB Minimum: 16KB Maximum: 2GB

md_sqm_write_request_limit

Specifies the amount of memory available to the Distributor for messages waiting to be written to the outbound queue.

Default: 1MB

Minimum: 16K

Maximum: 2GB

parallel_dsi

A shorthand method for configuring parallel DSI to default values. A value of “on” sets dsi_num_threads to 5, dsi_num_large_xact_threads to 2, dsi_serialization_method to wait_for_commit, and dsi_sqt_max_cache_size to 1 million bytes. A value of “off” sets the parallel DSI values to their defaults. You can set this parameter to “on” and then set individual parallel DSI configuration parameters to fine-tune your configuration.

Default: off

use_batch_markers

If use_batch_markers is set to on, the function strings rs_batch_start and rs_batch_end will be executed.

Default: off