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Add header matching mode to COPY FROM

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COPY FROM supports the HEADER option to silently discard the header
line from a CSV or text file.  It is possible to load by mistake a
file that matches the expected format, for example, if two text
columns have been swapped, resulting in garbage in the database.

This adds a new option value HEADER MATCH that checks the column names
in the header line against the actual column names and errors out if
they do not match.

Author: Rémi Lapeyre <remi.lapeyre@lenstra.fr>
Reviewed-by: Daniel Verite <daniel@manitou-mail.org>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/CAF1-J-0PtCWMeLtswwGV2M70U26n4g33gpe1rcKQqe6wVQDrFA@mail.gmail.com
This commit is contained in:
Peter Eisentraut
2022-03-30 08:56:58 +02:00
parent edcedcc2c7
commit 072132f04e
8 changed files with 210 additions and 8 deletions
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60
src/backend/commands/copy.c
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@ -313,6 +313,64 @@ DoCopy(ParseState *pstate, const CopyStmt *stmt,
table_close(rel, NoLock);
}
/*
* Extract a CopyHeaderChoice value from a DefElem. This is like
* defGetBoolean() but also accepts the special value "match".
*/
static CopyHeaderChoice
defGetCopyHeaderChoice(DefElem *def)
{
/*
* If no parameter given, assume "true" is meant.
*/
if (def->arg == NULL)
return COPY_HEADER_TRUE;
/*
* Allow 0, 1, "true", "false", "on", "off", or "match".
*/
switch (nodeTag(def->arg))
{
case T_Integer:
switch (intVal(def->arg))
{
case 0:
return COPY_HEADER_FALSE;
case 1:
return COPY_HEADER_TRUE;
default:
/* otherwise, error out below */
break;
}
break;
default:
{
char *sval = defGetString(def);
/*
* The set of strings accepted here should match up with the
* grammar's opt_boolean_or_string production.
*/
if (pg_strcasecmp(sval, "true") == 0)
return COPY_HEADER_TRUE;
if (pg_strcasecmp(sval, "false") == 0)
return COPY_HEADER_FALSE;
if (pg_strcasecmp(sval, "on") == 0)
return COPY_HEADER_TRUE;
if (pg_strcasecmp(sval, "off") == 0)
return COPY_HEADER_FALSE;
if (pg_strcasecmp(sval, "match") == 0)
return COPY_HEADER_MATCH;
}
break;
}
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("%s requires a Boolean value or \"match\"",
def->defname)));
return COPY_HEADER_FALSE; /* keep compiler quiet */
}
/*
* Process the statement option list for COPY.
*
@ -394,7 +452,7 @@ ProcessCopyOptions(ParseState *pstate,
if (header_specified)
errorConflictingDefElem(defel, pstate);
header_specified = true;
opts_out->header_line = defGetBoolean(defel);
opts_out->header_line = defGetCopyHeaderChoice(defel);
}
else if (strcmp(defel->defname, "quote") == 0)
{