From b1b684ce962c24431a927274774a5e06f513f5e7 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Wed, 10 Feb 2021 16:56:17 -0500 Subject: [PATCH v24 05/10] fixups.patch --- doc/src/sgml/ddl.sgml | 3 --- doc/src/sgml/ref/create_table.sgml | 15 +++++++++++---- src/backend/access/common/detoast.c | 5 ++--- src/backend/access/compression/compress_lz4.c | 10 +++++----- src/backend/executor/nodeModifyTable.c | 2 +- src/include/nodes/execnodes.h | 4 ++-- 6 files changed, 21 insertions(+), 18 deletions(-) diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml index 4d7ed698b9..1e9a4625cc 100644 --- a/doc/src/sgml/ddl.sgml +++ b/doc/src/sgml/ddl.sgml @@ -3762,9 +3762,6 @@ CREATE TABLE measurement ( PostgreSQL tables (or, possibly, foreign tables). It is possible to specify a tablespace and storage parameters for each partition separately. - By default, each column in a partition inherits the compression method - from parent table's column, however a different compression method can be - set for each partition. diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index 51a7a977a5..a4b297340f 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -997,10 +997,17 @@ WITH ( MODULUS numeric_literal, REM COMPRESSION compression_method - This sets the compression method for a column. The supported compression - methods are pglz and lz4. - lz4 is available only if --with-lz4 - was used when building PostgreSQL. The default + The COMPRESSION clause sets the compression method + for a column. Compression is supported only for variable-width data + types, and is used only for columns whose storage type is main or + extended. (See for information on + column storage types.) Setting this property for a partitioned table + has no direct effect, because such tables have no storage of their own, + but the configured value is inherited by newly-created partitions. + The supported compression methods are pglz and + lz4. lz4 is available only if + --with-lz4 was used when building + PostgreSQL. The default is pglz. diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c index b78d49167b..95d5b1c12a 100644 --- a/src/backend/access/common/detoast.c +++ b/src/backend/access/common/detoast.c @@ -477,8 +477,8 @@ toast_get_compression_oid(struct varlena *attr) return InvalidOid; /* - * Just fetch the toast compress header to know the compression method - * in the compressed data. + * Fetch just enough of the value to examine the compression header, + * so that we can find out the compression method. */ attr = toast_fetch_datum_slice(attr, 0, VARHDRSZ_COMPRESS); } @@ -503,7 +503,6 @@ toast_get_compression_handler(struct varlena *attr) cmid = TOAST_COMPRESS_METHOD(attr); - /* Get the handler routines for the compression method */ switch (cmid) { case PGLZ_COMPRESSION_ID: diff --git a/src/backend/access/compression/compress_lz4.c b/src/backend/access/compression/compress_lz4.c index 1856cf7df7..3079eff7eb 100644 --- a/src/backend/access/compression/compress_lz4.c +++ b/src/backend/access/compression/compress_lz4.c @@ -23,7 +23,7 @@ /* * lz4_cmcompress - compression routine for lz4 compression method * - * Compresses source into dest using the default strategy. Returns the + * Compresses source into dest using the LZ4 defaults. Returns the * compressed varlena, or NULL if compression fails. */ static struct varlena * @@ -42,8 +42,8 @@ lz4_cmcompress(const struct varlena *value) valsize = VARSIZE_ANY_EXHDR(value); /* - * Get maximum size of the compressed data that lz4 compression may output - * and allocate the memory for holding the compressed data and the header. + * Figure out the maximum possible size of the LZ4 output, add the bytes + * that will be needed for varlena overhead, and allocate that amount. */ max_size = LZ4_compressBound(valsize); tmp = (struct varlena *) palloc(max_size + VARHDRSZ_COMPRESS); @@ -83,10 +83,10 @@ lz4_cmdecompress(const struct varlena *value) int32 rawsize; struct varlena *result; - /* allocate memory for holding the uncompressed data */ + /* allocate memory for the uncompressed data */ result = (struct varlena *) palloc(VARRAWSIZE_4B_C(value) + VARHDRSZ); - /* decompress data using lz4 routine */ + /* decompress the data */ rawsize = LZ4_decompress_safe((char *) value + VARHDRSZ_COMPRESS, VARDATA(result), VARSIZE(value) - VARHDRSZ_COMPRESS, diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c index f77deee399..920d9dd0d5 100644 --- a/src/backend/executor/nodeModifyTable.c +++ b/src/backend/executor/nodeModifyTable.c @@ -2117,7 +2117,7 @@ CompareCompressionMethodAndDecompress(TupleTableSlot *slot, TupleTableSlot *newslot = *outslot; /* - * If the called has passed an invalid slot then create a new slot. + * If the caller has passed an invalid slot then create a new slot. * Otherwise, just clear the existing tuple from the slot. This slot * should be stored by the caller so that it can be reused for * decompressing the subsequent tuples. diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index 18e8ecfd90..d8483c36b3 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1183,8 +1183,8 @@ typedef struct ModifyTableState TupleTableSlot *mt_root_tuple_slot; /* - * Slot for storing the modified tuple, incase the target attribute's - * compression method doesn't match with the source table. + * Slot for storing the modified tuple, in case the target attribute's + * compression method doesn't match that of the source table. */ TupleTableSlot *mt_decompress_tuple_slot; -- 2.17.0