Re: EXPLAIN BUFFERS

Itagaki Takahiro escreveu:
> Here is an updated patch per discussion.
>
> * Counters are accumulative. They contain I/Os by child nodes.
> * Text format shows all counters.
> * Add "shared_" prefix to variables representing shared buffers/blocks.
>
Nice. Despite of the other opinions, I'm satisfied with your text format
sentence. It is: (i) clear (I don't have to think or check the docs to know
what information is that.) and (ii) not so verbose (There are nodes that are
even longer than that.).

The only thing that needs some fix is:

+ Include information on the buffers. Specifically, include the number of
+ hits/reads/writes of shared blocks and local blocks, and number of reads
+ and writes of temp blocks. Shared blocks contain global tables and
+ indexes, local blocks contain temporary tables and indexes, and temp
+ blocks contain disk blocks used in sort and materialized plans.
+ The value of a parent node contains values of its children.
+ This parameter should be used with <literal>ANALYZE</literal> parameter.
+ This parameter defaults to <literal>FALSE</literal>.

That could be:

Include information on the buffers. Specifically, include the number of shared
blocks hits, reads, and writes, the number of local blocks hits, reads, and
writes, and the number of temp blocks reads and writes. Shared blocks, local
blocks, and temp blocks contain tables and indexes, temporary tables and
temporary indexes, and disk blocks used in sort and materialized plans,
respectively. The number of blocks of an upper-level node includes the blocks
of all its child nodes. It should be used with <literal>ANALYZE</literal>
parameter. This parameter defaults to <literal>FALSE</literal>.

If there is no more objections, I'll flag the patch 'ready for committer' (you :).

--
Euler Taveira de Oliveira
http://www.timbira.com/