| From: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Blake McBride <blake1024(at)gmail(dot)com>, pgsql-general <pgsql-general(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Trouble incrementing a column |
| Date: | 2019-11-25 00:51:11 |
| Message-ID: | CAMkU=1w61H6siZF0f+UTSLp_e8=sM7SNT_aFsk6_8kipRsvQGw@mail.gmail.com |
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| Lists: | pgsql-general |
On Sat, Nov 23, 2019 at 4:47 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Note that you pay a fairly substantial performance penalty for deferring
> the check, which is why it isn't the default, even though the SQL spec
> says it ought to be.
>
Do you know what the worst case scenario is for the performance of
deferring the check to the end of the statement (with deferred initially
immediate)? Upon testing, I get a penalty of 2 to 5%, which seems pretty
small, but I might not be testing the most adverse situation. See attached.
The main "cost" that prevents from using DII routinely is that they can't
receive foreign key constraints.
Cheers,
Jeff
| Attachment | Content-Type | Size |
|---|---|---|
| bench_dii.sh | text/x-sh | 707 bytes |
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