|From:||Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>|
|To:||Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>|
|Cc:||Robert Haas <robertmhaas(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>|
|Subject:||Re: no partition pruning when partitioning using array type|
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Another thing I realized when testing this is that partitioning over a
domain doesn't work very nicely (tested in 10 and master):
create domain overint as int;
create table pt (a overint) partition by range (a);
create table pt1 partition of pt for values from (0) to (100);
ERROR: specified value cannot be cast to type overint for column "a"
LÍNEA 1: create table pt1 partition of pt for values from (0) to (100...
DETALLE: The cast requires a non-immutable conversion.
SUGERENCIA: Try putting the literal value in single quotes.
I tried to do what the HINT says, but it fails in the same way. I also
tried to add casts, but those are rejected as syntax errors.
Tracing it down, turns out that transformPartitionBoundValue gets from
coerce_to_target_type a CoerceToDomain node. It then tries to apply
expression_planner() to simplify the expression, but that one doesn't
want anything to do with a domain coercion (for apparently good reasons,
given other comments in that file). However, if we take out the
expression_planner() and replace it with a call to
strip_implicit_coercions(), not only it magically starts working, but
also the regression tests start failing with the attached diff, which
seems a Good Thing to me.
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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