diff options
Diffstat (limited to 'src/include/postgres.h')
| -rw-r--r-- | src/include/postgres.h | 50 |
1 files changed, 46 insertions, 4 deletions
diff --git a/src/include/postgres.h b/src/include/postgres.h index 2ed572004dd..2ccbea8e502 100644 --- a/src/include/postgres.h +++ b/src/include/postgres.h @@ -55,7 +55,9 @@ /* * struct varatt_external is a traditional "TOAST pointer", that is, the * information needed to fetch a Datum stored out-of-line in a TOAST table. - * The data is compressed if and only if va_extsize < va_rawsize - VARHDRSZ. + * The data is compressed if and only if the size stored in va_extinfo < + * va_rawsize - VARHDRSZ. + * * This struct must not contain any padding, because we sometimes compare * these pointers using memcmp. * @@ -67,7 +69,8 @@ typedef struct varatt_external { int32 va_rawsize; /* Original data size (includes header) */ - int32 va_extsize; /* External saved size (doesn't) */ + uint32 va_extinfo; /* External saved size (without header) and + * compression method */ Oid va_valueid; /* Unique ID of value within TOAST table */ Oid va_toastrelid; /* RelID of TOAST table containing it */ } varatt_external; @@ -145,7 +148,8 @@ typedef union struct /* Compressed-in-line format */ { uint32 va_header; - uint32 va_rawsize; /* Original data size (excludes header) */ + uint32 va_tcinfo; /* Original data size (excludes header) and + * compression method */ char va_data[FLEXIBLE_ARRAY_MEMBER]; /* Compressed data */ } va_compressed; } varattrib_4b; @@ -274,14 +278,23 @@ typedef struct (VARSIZE(PTR) - VARHDRSZ + VARHDRSZ_SHORT) #define VARHDRSZ_EXTERNAL offsetof(varattrib_1b_e, va_data) +#define VARHDRSZ_COMPRESS offsetof(varattrib_4b, va_compressed.va_data) #define VARDATA_4B(PTR) (((varattrib_4b *) (PTR))->va_4byte.va_data) #define VARDATA_4B_C(PTR) (((varattrib_4b *) (PTR))->va_compressed.va_data) #define VARDATA_1B(PTR) (((varattrib_1b *) (PTR))->va_data) #define VARDATA_1B_E(PTR) (((varattrib_1b_e *) (PTR))->va_data) +#define VARLENA_RAWSIZE_BITS 30 +#define VARLENA_RAWSIZE_MASK ((1U << VARLENA_RAWSIZE_BITS) - 1) + +/* + * va_tcinfo in va_compress contains raw size of datum and compression method. + */ #define VARRAWSIZE_4B_C(PTR) \ - (((varattrib_4b *) (PTR))->va_compressed.va_rawsize) + (((varattrib_4b *) (PTR))->va_compressed.va_tcinfo & VARLENA_RAWSIZE_MASK) +#define VARCOMPRESS_4B_C(PTR) \ + (((varattrib_4b *) (PTR))->va_compressed.va_tcinfo >> VARLENA_RAWSIZE_BITS) /* Externally visible macros */ @@ -323,6 +336,35 @@ typedef struct (VARATT_IS_EXTERNAL(PTR) && VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR))) #define VARATT_IS_EXTERNAL_NON_EXPANDED(PTR) \ (VARATT_IS_EXTERNAL(PTR) && !VARTAG_IS_EXPANDED(VARTAG_EXTERNAL(PTR))) + +/* + * va_extinfo in varatt_external contains actual length of the external data + * and compression method if external data is compressed. + */ +#define VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) \ + ((toast_pointer).va_extinfo & VARLENA_RAWSIZE_MASK) + +#define VARATT_EXTERNAL_SET_SIZE_AND_COMPRESSION(toast_pointer, len, cm) \ + do { \ + Assert((cm) == TOAST_PGLZ_COMPRESSION_ID || \ + (cm) == TOAST_LZ4_COMPRESSION_ID); \ + ((toast_pointer).va_extinfo = (len) | (cm) << VARLENA_RAWSIZE_BITS); \ + } while (0) + +#define VARATT_EXTERNAL_GET_COMPRESSION(PTR) \ + ((toast_pointer).va_extinfo >> VARLENA_RAWSIZE_BITS) + +/* + * Testing whether an externally-stored value is compressed now requires + * comparing size stored in va_extinfo (the actual length of the external data) + * to rawsize (the original uncompressed datum's size). The latter includes + * VARHDRSZ overhead, the former doesn't. We never use compression unless it + * actually saves space, so we expect either equality or less-than. + */ +#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \ + (VARATT_EXTERNAL_GET_EXTSIZE(toast_pointer) < \ + (toast_pointer).va_rawsize - VARHDRSZ) + #define VARATT_IS_SHORT(PTR) VARATT_IS_1B(PTR) #define VARATT_IS_EXTENDED(PTR) (!VARATT_IS_4B_U(PTR)) |