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* Document Upper Limit for NAMEDATELEN in pgsql 9.5+
@ 2016-01-08 19:29 Kevin Day <thekevinday@gmail.com>
0 siblings, 1 reply; 2+ messages in thread
From: Kevin Day @ 2016-01-08 19:29 UTC (permalink / raw)
To: pgsql-docs
Postgresql 9.5+ may now fail to compile if NAMEDATELEN has been set
absurdly large (In my case, 384).
The file src/backend/utils/adt/levenshtein.c does a static assert on
"NAMEDATALEN <= MAX_LEVENSHTEIN_STRLEN" with MAX_LEVENSHTEIN_STRLEN
currently set to 255.
When using a gcc version that does not support static asserts, the error
message looks like:
- "levenshtein.c:104: error: negative width in bit-field
'static_assert_failure'"
It would be great to be mention this new upper limit on NAMEDATALEN in the
documentation.
Here are some places I've looked at:
- src/include/pg_config_manual.h
- http://www.postgresql.org/docs/9.5/static/sql-syntax-lexical.html
- http://www.postgresql.org/docs/9.5/static/runtime-config-preset.html
- https://wiki.postgresql.org/wiki/Todo
While on the subject of NAMEDATALEN, there is a second undocumented place
where NAMEDATALEN is defined:
- src/interfaces/ecpg/include/sqlda-native.h
--
Kevin Day
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Document Upper Limit for NAMEDATELEN in pgsql 9.5+
@ 2016-01-08 19:49 Tom Lane <tgl@sss.pgh.pa.us>
parent: Kevin Day <thekevinday@gmail.com>
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2016-01-08 19:49 UTC (permalink / raw)
To: Kevin Day <thekevinday@gmail.com>; +Cc: pgsql-docs
Kevin Day <thekevinday@gmail.com> writes:
> Postgresql 9.5+ may now fail to compile if NAMEDATELEN has been set
> absurdly large (In my case, 384).
> The file src/backend/utils/adt/levenshtein.c does a static assert on
> "NAMEDATALEN <= MAX_LEVENSHTEIN_STRLEN" with MAX_LEVENSHTEIN_STRLEN
> currently set to 255.
Hmm. I'm not sure whether 384 is "absurdly large", but I do wonder
why the levenshtein code gets to dictate limits on NAMEDATALEN at all.
Or to put it even more bluntly, I'm not sure that there is anything
whatever about MAX_LEVENSHTEIN_STRLEN that is well thought out. Why not
rip it out and put some CHECK_FOR_INTERRUPTS tests into the loops instead?
regards, tom lane
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2016-01-08 19:29 Document Upper Limit for NAMEDATELEN in pgsql 9.5+ Kevin Day <thekevinday@gmail.com>
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