diff options
Diffstat (limited to 'src/backend/utils/adt/varchar.c')
| -rw-r--r-- | src/backend/utils/adt/varchar.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c index 1c0ef921a71..efa483d638d 100644 --- a/src/backend/utils/adt/varchar.c +++ b/src/backend/utils/adt/varchar.c @@ -18,6 +18,8 @@ #include "access/hash.h" #include "access/tuptoaster.h" #include "libpq/pqformat.h" +#include "nodes/nodeFuncs.h" +#include "parser/parse_clause.h" #include "utils/array.h" #include "utils/builtins.h" #include "mb/pg_wchar.h" @@ -549,6 +551,38 @@ varcharsend(PG_FUNCTION_ARGS) /* + * Flatten calls to our length coercion function that leave the new maximum + * length >= the previous maximum length. We ignore the isExplicit argument, + * which only affects truncation. + */ +Datum +varchar_transform(PG_FUNCTION_ARGS) +{ + FuncExpr *expr = (FuncExpr *) PG_GETARG_POINTER(0); + Node *typmod; + Node *ret = NULL; + + if (!IsA(expr, FuncExpr)) + PG_RETURN_POINTER(ret); + + Assert(list_length(expr->args) == 3); + typmod = lsecond(expr->args); + + if (IsA(typmod, Const)) + { + Node *source = linitial(expr->args); + int32 new_typmod = DatumGetInt32(((Const *) typmod)->constvalue); + int32 old_max = exprTypmod(source) - VARHDRSZ; + int32 new_max = new_typmod - VARHDRSZ; + + if (new_max < 0 || (old_max >= 0 && old_max <= new_max)) + ret = relabel_to_typmod(source, new_typmod); + } + + PG_RETURN_POINTER(ret); +} + +/* * Converts a VARCHAR type to the specified size. * * maxlen is the typmod, ie, declared length plus VARHDRSZ bytes. |