database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-07 00:36:50 +03:00
Code Activity

Allow COPY FROM to filter data using WHERE conditions

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

10
src/backend/parser/gram.y
View File

@ -2962,7 +2962,8 @@ ClosePortalStmt:
*****************************************************************************/
CopyStmt: COPY opt_binary qualified_name opt_column_list
copy_from opt_program copy_file_name copy_delimiter opt_with copy_options
copy_from opt_program copy_file_name copy_delimiter opt_with
copy_options where_clause
{
CopyStmt *n = makeNode(CopyStmt);
n->relation = $3;
@ -2971,6 +2972,7 @@ CopyStmt: COPY opt_binary qualified_name opt_column_list
n->is_from = $5;
n->is_program = $6;
n->filename = $7;
n->whereClause = $11;
if (n->is_program && n->filename == NULL)
ereport(ERROR,
@ -2978,6 +2980,12 @@ CopyStmt: COPY opt_binary qualified_name opt_column_list
errmsg("STDIN/STDOUT not allowed with PROGRAM"),
parser_errposition(@8)));
if (!n->is_from && n->whereClause != NULL)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("WHERE clause not allowed with COPY TO"),
parser_errposition(@11)));
n->options = NIL;
/* Concatenate user-supplied flags */
if ($2)

11
src/backend/parser/parse_agg.c
View File

@ -523,6 +523,14 @@ check_agglevels_and_constraints(ParseState *pstate, Node *expr)
break;
case EXPR_KIND_COPY_WHERE:
if (isAgg)
err = _("aggregate functions are not allowed in COPY FROM WHERE conditions");
else
err = _("grouping operations are not allowed in COPY FROM WHERE conditions");
break;
/*
* There is intentionally no default: case here, so that the
* compiler will warn if we add a new ParseExprKind without
@ -902,6 +910,9 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
case EXPR_KIND_CALL_ARGUMENT:
err = _("window functions are not allowed in CALL arguments");
break;
case EXPR_KIND_COPY_WHERE:
err = _("window functions are not allowed in COPY FROM WHERE conditions");
break;
/*
* There is intentionally no default: case here, so that the

5
src/backend/parser/parse_expr.c
View File

@ -1849,6 +1849,9 @@ transformSubLink(ParseState *pstate, SubLink *sublink)
case EXPR_KIND_CALL_ARGUMENT:
err = _("cannot use subquery in CALL argument");
break;
case EXPR_KIND_COPY_WHERE:
err = _("cannot use subquery in COPY FROM WHERE condition");
break;
/*
* There is intentionally no default: case here, so that the
@ -3475,6 +3478,8 @@ ParseExprKindName(ParseExprKind exprKind)
return "PARTITION BY";
case EXPR_KIND_CALL_ARGUMENT:
return "CALL";
case EXPR_KIND_COPY_WHERE:
return "WHERE";
/*
* There is intentionally no default: case here, so that the

3
src/backend/parser/parse_func.c
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