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Allow COPY FROM to filter data using WHERE conditions

Extends the COPY FROM command with a WHERE condition, which allows doing
various types of filtering while importing the data (random sampling,
condition on a data column, etc.).  Until now such filtering required
either preprocessing of the input data, or importing all data and then
filtering in the database. COPY FROM ... WHERE is an easy-to-use and
low-overhead alternative for most simple cases.

Author: Surafel Temesgen
Reviewed-by: Tomas Vondra, Masahiko Sawada, Lim Myungkyu
Discussion: https://www.postgresql.org/message-id/flat/CALAY4q_DdpWDuB5-Zyi-oTtO2uSk8pmy+dupiRe3AvAc++1imA@mail.gmail.com
This commit is contained in:
Tomas Vondra
2019-01-19 23:48:16 +01:00
parent d6ef7fe75c
commit 31f3817402
13 changed files with 175 additions and 4 deletions

View File

@ -2370,6 +2370,9 @@ check_srf_call_placement(ParseState *pstate, Node *last_srf, int location)
case EXPR_KIND_CALL_ARGUMENT:
err = _("set-returning functions are not allowed in CALL arguments");
break;
case EXPR_KIND_COPY_WHERE:
err = _("set-returning functions are not allowed in COPY FROM WHERE conditions");
break;
/*
* There is intentionally no default: case here, so that the