Refactor reloption handling for index AMs in-core

This reworks the reloption parsing and build of a couple of index AMs by
creating new structures for each index AM's options.  This split was
already done for BRIN, GIN and GiST (which actually has a fillfactor
parameter), but not for hash, B-tree and SPGiST which relied on
StdRdOptions due to an overlap with the default option set.

This saves a couple of bytes for rd_options in each relcache entry with
indexes making use of relation options, and brings more consistency
between all index AMs.  While on it, add a couple of AssertMacro() calls
to make sure that utility macros to grab values of reloptions are used
with the expected index AM.

Author: Nikolay Shaplov
Reviewed-by: Amit Langote, Michael Paquier, Álvaro Herrera, Dent John
Discussion: https://postgr.es/m/4127670.gFlpRb6XCm@x200m

src/include/access/brin.h

@@ -37,11 +37,15 @@ typedef struct BrinStatsData
 
 #define BRIN_DEFAULT_PAGES_PER_RANGE	128
 #define BrinGetPagesPerRange(relation) \
-	((relation)->rd_options ? \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == BRIN_AM_OID), \
+	 (relation)->rd_options ? \
 	 ((BrinOptions *) (relation)->rd_options)->pagesPerRange : \
 	  BRIN_DEFAULT_PAGES_PER_RANGE)
 #define BrinGetAutoSummarize(relation) \
-	((relation)->rd_options ? \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == BRIN_AM_OID), \
+	 (relation)->rd_options ? \
 	 ((BrinOptions *) (relation)->rd_options)->autosummarize : \
 	  false)
 

src/include/access/gin_private.h

@@ -14,6 +14,7 @@
 #include "access/gin.h"
 #include "access/ginblock.h"
 #include "access/itup.h"
+#include "catalog/pg_am_d.h"
 #include "fmgr.h"
 #include "storage/bufmgr.h"
 #include "lib/rbtree.h"
@@ -30,10 +31,14 @@ typedef struct GinOptions
 
 #define GIN_DEFAULT_USE_FASTUPDATE	true
 #define GinGetUseFastUpdate(relation) \
-	((relation)->rd_options ? \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == GIN_AM_OID), \
+	 (relation)->rd_options ? \
 	 ((GinOptions *) (relation)->rd_options)->useFastUpdate : GIN_DEFAULT_USE_FASTUPDATE)
 #define GinGetPendingListCleanupSize(relation) \
-	((relation)->rd_options && \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == GIN_AM_OID), \
+	 (relation)->rd_options && \
 	 ((GinOptions *) (relation)->rd_options)->pendingListCleanupSize != -1 ? \
 	 ((GinOptions *) (relation)->rd_options)->pendingListCleanupSize : \
 	 gin_pending_list_limit)

src/include/access/hash.h

@@ -20,6 +20,7 @@
 #include "access/amapi.h"
 #include "access/itup.h"
 #include "access/sdir.h"
+#include "catalog/pg_am_d.h"
 #include "lib/stringinfo.h"
 #include "storage/bufmgr.h"
 #include "storage/lockdefs.h"
@@ -263,6 +264,21 @@ typedef struct HashMetaPageData
 
 typedef HashMetaPageData *HashMetaPage;
 
+typedef struct HashOptions
+{
+	int32		varlena_header_;	/* varlena header (do not touch directly!) */
+	int			fillfactor;		/* page fill factor in percent (0..100) */
+} HashOptions;
+
+#define HashGetFillFactor(relation) \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == HASH_AM_OID), \
+	 (relation)->rd_options ? \
+	 ((HashOptions *) (relation)->rd_options)->fillfactor :	\
+	 HASH_DEFAULT_FILLFACTOR)
+#define HashGetTargetPageUsage(relation) \
+	(BLCKSZ * HashGetFillFactor(relation) / 100)
+
 /*
  * Maximum size of a hash index item (it's okay to have only one per page)
  */

src/include/access/nbtree.h

@@ -18,6 +18,7 @@
 #include "access/itup.h"
 #include "access/sdir.h"
 #include "access/xlogreader.h"
+#include "catalog/pg_am_d.h"
 #include "catalog/pg_index.h"
 #include "lib/stringinfo.h"
 #include "storage/bufmgr.h"
@@ -680,6 +681,23 @@ typedef BTScanOpaqueData *BTScanOpaque;
 #define SK_BT_DESC			(INDOPTION_DESC << SK_BT_INDOPTION_SHIFT)
 #define SK_BT_NULLS_FIRST	(INDOPTION_NULLS_FIRST << SK_BT_INDOPTION_SHIFT)
 
+typedef struct BTOptions
+{
+	int32		varlena_header_;	/* varlena header (do not touch directly!) */
+	int			fillfactor;		/* page fill factor in percent (0..100) */
+	/* fraction of newly inserted tuples prior to trigger index cleanup */
+	float8		vacuum_cleanup_index_scale_factor;
+} BTOptions;
+
+#define BTGetFillFactor(relation) \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == BTREE_AM_OID), \
+	 (relation)->rd_options ? \
+	 ((BTOptions *) (relation)->rd_options)->fillfactor : \
+	 BTREE_DEFAULT_FILLFACTOR)
+#define BTGetTargetPageFreeSpace(relation) \
+	(BLCKSZ * (100 - BTGetFillFactor(relation)) / 100)
+
 /*
  * Constant definition for progress reporting.  Phase numbers must match
  * btbuildphasename.

src/include/access/spgist.h

@@ -19,10 +19,6 @@
 #include "lib/stringinfo.h"
 
 
-/* reloption parameters */
-#define SPGIST_MIN_FILLFACTOR			10
-#define SPGIST_DEFAULT_FILLFACTOR		80
-
 /* SPGiST opclass support function numbers */
 #define SPGIST_CONFIG_PROC				1
 #define SPGIST_CHOOSE_PROC				2

src/include/access/spgist_private.h

@@ -16,12 +16,29 @@
 
 #include "access/itup.h"
 #include "access/spgist.h"
+#include "catalog/pg_am_d.h"
 #include "nodes/tidbitmap.h"
 #include "storage/buf.h"
 #include "utils/geo_decls.h"
 #include "utils/relcache.h"
 
 
+typedef struct SpGistOptions
+{
+	int32		varlena_header_;	/* varlena header (do not touch directly!) */
+	int			fillfactor;		/* page fill factor in percent (0..100) */
+} SpGistOptions;
+
+#define SpGistGetFillFactor(relation) \
+	(AssertMacro(relation->rd_rel->relkind == RELKIND_INDEX && \
+				 relation->rd_rel->relam == SPGIST_AM_OID), \
+	 (relation)->rd_options ? \
+	 ((SpGistOptions *) (relation)->rd_options)->fillfactor : \
+	 SPGIST_DEFAULT_FILLFACTOR)
+#define SpGistGetTargetPageFreeSpace(relation) \
+	(BLCKSZ * (100 - SpGistGetFillFactor(relation)) / 100)
+
+
 /* Page numbers of fixed-location pages */
 #define SPGIST_METAPAGE_BLKNO	 (0)	/* metapage */
 #define SPGIST_ROOT_BLKNO		 (1)	/* root for normal entries */
@@ -423,6 +440,11 @@ typedef SpGistDeadTupleData *SpGistDeadTuple;
 #define GBUF_REQ_NULLS(flags)	((flags) & GBUF_NULLS)
 
 /* spgutils.c */
+
+/* reloption parameters */
+#define SPGIST_MIN_FILLFACTOR			10
+#define SPGIST_DEFAULT_FILLFACTOR		80
+
 extern SpGistCache *spgGetCache(Relation index);
 extern void initSpGistState(SpGistState *state, Relation index);
 extern Buffer SpGistNewBuffer(Relation index);