the Postgresql version is 13.6
and the DECLARE COMMAND IS
declare sdx_3a6c_8 no scroll binary cursor without hold for select "roalkL"."smid","roalkL"."smgeometry" from "public"."roalkL" where "roalkL"."smgeometry" && st_makeenvelope(321673.3153346270555630,3375950.6560412631370127,367212.1915803211741149,3402758.1912380573339760,32649)
the data might be 1GB,and we need get all in about 10 seconds.
Adrian Klaver <adrian.klaver@xxxxxxxxxxx> 于2023年4月14日周五 23:11写道：
On 4/14/23 04:04, 黄宁 wrote:
> i want to use cursor with hold ,but when I declare a curosr , it takes a
> long time to save the result set to disk. can i save the query state in
> memory? and fetch forward the next result.
>
From the docs:
https://www.postgresql.org/docs/current/sql-declare.html
A cursor created with WITH HOLD is closed when an explicit CLOSE command
is issued on it, or the session ends. In the current implementation, the
rows represented by a held cursor are copied into a temporary file or
memory area so that they remain available for subsequent transactions.
So I am going to guess the cursor query is holding a large amount of data.
To get a more specific answer you will need to provide:
1) Postgres version.
2) The complete DECLARE command being used.
3) An indication of the amount of data being retrieved.
4) The actual time for a 'long time'.
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
