Maximum number of connections allowed in the connection pool on a secondary node.
Can be set only for the PUBLIC group. Requires DBA permissions to set the option. Setting takes effect immediately and persists across server restarts.
INC connections are inter-server connections between secondary nodes and the coordinator node. An INC connection is associated with each user connection on a secondary server doing a DDL or read-write operation. The connection is active until that command commits or rolls back; it then returns to the pool. If these transactions are short lived, then the default setting of MPX_MAX_CONNECTION_POOL_SIZE suffices for many user connections running DDL or RW operations. If many concurrent connections run DDL or read-write operations, or the transactions take a long time, increase the value of MPX_MAX_CONNECTION_POOL_SIZE. For example, increase the value when many user connections do concurrent loads without committing.
Exceeding MPX_MAX_CONNECTION_POOL_SIZE returns SQL Anywhere Error -1004000: The number of connections in the connection pool have exceeded the upper limit.
To estimate the pool size required, consider the setting of the -gm server option. The -gm setting indicates how many users can connect to the secondary server; the INC connections are not included, but will add to this number. Use application requirements to assess how many read-write or DDL operations are likely to occur per user, and increase the pool size accordingly.
Each connection (INC or user) carries a memory overhead depending on -gn setting and number of cores. The burden of memory and thread contention may affect Sybase IQ server response times. See Performance and Tuning Guide > Managing System Resources > Optimize Memory Use > Determine the Sizes of the Buffer Caches > Memory Overhead.