Re: Small run-time pruning doc fix
On 13 November 2018 at 02:46, Peter Eisentraut wrote: > Committed your change. Thanks. -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
Re: Small run-time pruning doc fix
On 04/11/2018 06:23, David Rowley wrote: > Thanks for looking at this. > > On 2 November 2018 at 20:30, Peter Eisentraut > wrote: >> >> - Execution-time partition pruning currently occurs for the >> + Execution-time partition pruning currently only occurs for the >> Append and MergeAppend node >> types. >> + It is not yet implemented for the ModifyTable node >> + type. >> >> >> Isn't this implied by the preceding paragraph >> >> Currently, pruning of partitions during the planning of an UPDATE or >> DELETE command is implemented using the constraint exclusion method > > That paragraph is talking about plan-time partition pruning. The > paragraph the patch changes is mentioning execution-time partition > pruning. In PG11 we have plan-time partition pruning for Append and > MergeAppend. UPDATE/DELETE does pruning, but it uses the constraint > exclusion code which does not work for HASH partitioned tables. In > PG11 we only have run-time partition pruning for Append. MergeAppend > support was only added in 5220bb7533 (PG12). I see now. The actual documentation change was separate in db72302b0a8. Committed your change. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
Re: Small run-time pruning doc fix
Thanks for looking at this. On 2 November 2018 at 20:30, Peter Eisentraut wrote: > > - Execution-time partition pruning currently occurs for the > + Execution-time partition pruning currently only occurs for the > Append and MergeAppend node > types. > + It is not yet implemented for the ModifyTable node > + type. > > > Isn't this implied by the preceding paragraph > > Currently, pruning of partitions during the planning of an UPDATE or > DELETE command is implemented using the constraint exclusion method That paragraph is talking about plan-time partition pruning. The paragraph the patch changes is mentioning execution-time partition pruning. In PG11 we have plan-time partition pruning for Append and MergeAppend. UPDATE/DELETE does pruning, but it uses the constraint exclusion code which does not work for HASH partitioned tables. In PG11 we only have run-time partition pruning for Append. MergeAppend support was only added in 5220bb7533 (PG12). > Also, could there be other node types that could benefit from partition > pruning that are not implemented yet? Not sure we want to mention all > of them. I'm unsure what might exist in the future, but there are currently only 3 node types that take a list of subpaths. I think if we get the support for ModifyTable later, then likely the paragraph edited in this patch would disappear. In fact, the entire note would disappear as adding run-time pruning for ModifyTable will require the planner to use the new partition pruning code. There's a patch for that in [1], so maybe it'll all be a little less confusing in PG12. [1] https://commitfest.postgresql.org/20/1778/ -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
Re: Small run-time pruning doc fix
On 08/10/2018 10:22, David Rowley wrote: > Before 5220bb7533f a note in ddl.sgml used to mention that run-time > pruning was only implemented for Append. When we got MergeAppend > support the commit updated this to mention MergeAppend is supported > too. This is slightly weird as it's not all that obvious what exactly > isn't supported when we mention: > > > Both of these behaviors are likely to be changed in a future release > of PostgreSQL. > > > The attached patch updates this to mention that ModifyTable is > unsupported which I think makes the above fragment make sense again. - Execution-time partition pruning currently occurs for the + Execution-time partition pruning currently only occurs for the Append and MergeAppend node types. + It is not yet implemented for the ModifyTable node + type. Isn't this implied by the preceding paragraph Currently, pruning of partitions during the planning of an UPDATE or DELETE command is implemented using the constraint exclusion method ? Also, could there be other node types that could benefit from partition pruning that are not implemented yet? Not sure we want to mention all of them. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
