diff options
Diffstat (limited to 'src/backend/utils/adt')
| -rw-r--r-- | src/backend/utils/adt/format_type.c | 50 |
1 files changed, 49 insertions, 1 deletions
diff --git a/src/backend/utils/adt/format_type.c b/src/backend/utils/adt/format_type.c index 003ab35aa18..19a8849b813 100644 --- a/src/backend/utils/adt/format_type.c +++ b/src/backend/utils/adt/format_type.c @@ -8,7 +8,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/adt/format_type.c,v 1.3 2000/08/21 18:23:18 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/format_type.c,v 1.4 2000/08/25 18:05:54 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -20,6 +20,7 @@ #include "fmgr.h" #include "catalog/pg_type.h" #include "utils/builtins.h" +#include "utils/numeric.h" #include "utils/syscache.h" #define MAX_INT32_LEN 11 @@ -214,6 +215,53 @@ format_type_internal(Oid type_oid, int32 typemod) } +/* + * type_maximum_size --- determine maximum length of a varlena column + * + * If the max length is indeterminate, return -1. In particular, we return + * -1 for any type not known to this routine. We assume the caller has + * already determined that the type is a varlena type, so it's not + * necessary to look up the type's pg_type tuple here. + * + * This may appear unrelated to format_type(), but in fact the two routines + * share knowledge of the encoding of typmod for different types, so it's + * convenient to keep them together. + */ +int32 +type_maximum_size(Oid type_oid, int32 typemod) +{ + if (typemod <= 0) + return -1; + + switch (type_oid) + { + case BPCHAROID: + case VARCHAROID: + /* typemod includes varlena header */ + return typemod; + + case NUMERICOID: + /* precision (ie, max # of digits) is in upper bits of typmod */ + if (typemod > VARHDRSZ) + { + int precision = ((typemod - VARHDRSZ) >> 16) & 0xffff; + + /* Numeric stores 2 decimal digits/byte, plus header */ + return (precision + 1) / 2 + NUMERIC_HDRSZ; + } + break; + + case VARBITOID: + case ZPBITOID: + /* typemod is the (max) number of bits */ + return (typemod + (BITSPERBYTE-1)) / BITSPERBYTE + + 2 * sizeof(int32); + } + + /* Unknown type, or unlimited-length type such as 'text' */ + return -1; +} + /* * oidvectortypes - converts a vector of type OIDs to "typname" list |