Improved EXPLAIN

The EXPLAIN improvements make the EXPLAIN output for FORMAT TEXT more readable and amend each plan node with information about self time and misestimate.

Self time is the time that was actually spent in the plan node itself, without the time spent in any of the child nodes. Misestimate is the ratio of planned rows vs. rows actually processed during execution. The self time is only displayed if the EXPLAIN arguments TIMING and COSTS are both enabled.

Amending the plan with extra information is only supported on CPUs with an invariant Time Stamp Counter (TSC). The TSC is needed for obtaining time measurements with low overhead.

Note, that some online tools for analyzing EPAS EXPLAIN output can fail with amended EXPLAIN output. If this is the case deactivate the additional plan node information via swarm64da.enable_extra_explain_info.

Settings

swarm64da.enable_explain_readability (boolean)

Enables or disables making the EXPLAIN output more readable by replacing Custom Scan Provider nodes with their custom names (e.g. S64 DA Hash Join instead of Custom Scan (S64 DA Hash Join)). The default is on.

swarm64da.enable_extra_explain_info (boolean)

Enables or disables amending every plan node in the EXPLAIN output with information about self time and misestimate. The default is off.