diff options
Diffstat (limited to 'src/backend/access/common/toast_internals.c')
| -rw-r--r-- | src/backend/access/common/toast_internals.c | 77 |
1 files changed, 45 insertions, 32 deletions
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c index 9b9da0f41bc..c81ce178221 100644 --- a/src/backend/access/common/toast_internals.c +++ b/src/backend/access/common/toast_internals.c @@ -44,46 +44,54 @@ static bool toastid_valueid_exists(Oid toastrelid, Oid valueid); * ---------- */ Datum -toast_compress_datum(Datum value) +toast_compress_datum(Datum value, char cmethod) { - struct varlena *tmp; - int32 valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value)); - int32 len; + struct varlena *tmp = NULL; + int32 valsize; + ToastCompressionId cmid = TOAST_INVALID_COMPRESSION_ID; Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value))); Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value))); + Assert(CompressionMethodIsValid(cmethod)); + + valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value)); + /* - * No point in wasting a palloc cycle if value size is out of the allowed - * range for compression + * Call appropriate compression routine for the compression method. */ - if (valsize < PGLZ_strategy_default->min_input_size || - valsize > PGLZ_strategy_default->max_input_size) - return PointerGetDatum(NULL); + switch (cmethod) + { + case TOAST_PGLZ_COMPRESSION: + tmp = pglz_compress_datum((const struct varlena *) value); + cmid = TOAST_PGLZ_COMPRESSION_ID; + break; + case TOAST_LZ4_COMPRESSION: + tmp = lz4_compress_datum((const struct varlena *) value); + cmid = TOAST_LZ4_COMPRESSION_ID; + break; + default: + elog(ERROR, "invalid compression method %c", cmethod); + } - tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) + - TOAST_COMPRESS_HDRSZ); + if (tmp == NULL) + return PointerGetDatum(NULL); /* - * We recheck the actual size even if pglz_compress() reports success, - * because it might be satisfied with having saved as little as one byte - * in the compressed data --- which could turn into a net loss once you - * consider header and alignment padding. Worst case, the compressed - * format might require three padding bytes (plus header, which is - * included in VARSIZE(tmp)), whereas the uncompressed format would take - * only one header byte and no padding if the value is short enough. So - * we insist on a savings of more than 2 bytes to ensure we have a gain. + * We recheck the actual size even if compression reports success, because + * it might be satisfied with having saved as little as one byte in the + * compressed data --- which could turn into a net loss once you consider + * header and alignment padding. Worst case, the compressed format might + * require three padding bytes (plus header, which is included in + * VARSIZE(tmp)), whereas the uncompressed format would take only one + * header byte and no padding if the value is short enough. So we insist + * on a savings of more than 2 bytes to ensure we have a gain. */ - len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)), - valsize, - TOAST_COMPRESS_RAWDATA(tmp), - PGLZ_strategy_default); - if (len >= 0 && - len + TOAST_COMPRESS_HDRSZ < valsize - 2) + if (VARSIZE(tmp) < valsize - 2) { - TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize); - SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ); /* successful compression */ + Assert(cmid != TOAST_INVALID_COMPRESSION_ID); + TOAST_COMPRESS_SET_SIZE_AND_METHOD(tmp, valsize, cmid); return PointerGetDatum(tmp); } else @@ -152,19 +160,21 @@ toast_save_datum(Relation rel, Datum value, &num_indexes); /* - * Get the data pointer and length, and compute va_rawsize and va_extsize. + * Get the data pointer and length, and compute va_rawsize and va_extinfo. * * va_rawsize is the size of the equivalent fully uncompressed datum, so * we have to adjust for short headers. * - * va_extsize is the actual size of the data payload in the toast records. + * va_extinfo stored the actual size of the data payload in the toast + * records and the compression method in first 2 bits if data is + * compressed. */ if (VARATT_IS_SHORT(dval)) { data_p = VARDATA_SHORT(dval); data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT; toast_pointer.va_rawsize = data_todo + VARHDRSZ; /* as if not short */ - toast_pointer.va_extsize = data_todo; + toast_pointer.va_extinfo = data_todo; } else if (VARATT_IS_COMPRESSED(dval)) { @@ -172,7 +182,10 @@ toast_save_datum(Relation rel, Datum value, data_todo = VARSIZE(dval) - VARHDRSZ; /* rawsize in a compressed datum is just the size of the payload */ toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ; - toast_pointer.va_extsize = data_todo; + + /* set external size and compression method */ + VARATT_EXTERNAL_SET_SIZE_AND_COMPRESSION(toast_pointer, data_todo, + VARCOMPRESS_4B_C(dval)); /* Assert that the numbers look like it's compressed */ Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer)); } @@ -181,7 +194,7 @@ toast_save_datum(Relation rel, Datum value, data_p = VARDATA(dval); data_todo = VARSIZE(dval) - VARHDRSZ; toast_pointer.va_rawsize = VARSIZE(dval); - toast_pointer.va_extsize = data_todo; + toast_pointer.va_extinfo = data_todo; } /* |