From a7782744d41900e4c82e43ac4b880bc217c9f8a0 Mon Sep 17 00:00:00 2001
From: dan <Dan Kennedy>
Date: Wed, 18 Dec 2024 20:23:05 +0000
Subject: [PATCH] Experimental: If SQLite is compiled with SQLITE_WAL_BIGHASH
 defined, use hash tables large enough to fit 128K, instead of 4K, entries in
 the *-shm file.

FossilOrigin-Name: 0cb853ea1dece578ae8f336c7d003e618d94ba003e25e5f5f307d7424f31b53f
---
 manifest      | 16 +++++++++-------
 manifest.uuid |  2 +-
 src/wal.c     | 30 +++++++++++++++++++++++-------
 3 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/manifest b/manifest
index 2f7a36d430..774312be59 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Optimize\sdeferred\sallocation\sof\spages\son\sthis\sbranch\sby\savoiding\sBTALLOC_LE.
-D 2024-12-16T20:30:06.892
+C Experimental:\sIf\sSQLite\sis\scompiled\swith\sSQLITE_WAL_BIGHASH\sdefined,\suse\shash\ntables\slarge\senough\sto\sfit\s128K,\sinstead\sof\s4K,\sentries\sin\sthe\s*-shm\sfile.
+D 2024-12-18T20:23:05.085
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md e108e1e69ae8e8a59e93c455654b8ac9356a11720d3345df2a4743e9590fb20d
@@ -866,7 +866,7 @@ F src/vdbetrace.c fe0bc29ebd4e02c8bc5c1945f1d2e6be5927ec12c06d89b03ef2a4def34bf8
 F src/vdbevtab.c fc46b9cbd759dc013f0b3724549cc0d71379183c667df3a5988f7e2f1bd485f3
 F src/vtab.c 316cd48e9320660db3047cd306cd056e4361180cebb4d0f10a39244e10c11422
 F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
-F src/wal.c 964c785ac8324de1ae742c44aa72ddd4401d4abab11ef6999aec21d7221b3e67
+F src/wal.c 8a0f98b271f992b67e4dab4ed1e88698ebf7e5bdf1fb8b39a94b3de92c9bd27e
 F src/wal.h 8d02ab8c2a93a941f5898eb3345bf711c1d3f8f86f4be8d5428fb6c074962d8a
 F src/walker.c d5006d6b005e4ea7302ad390957a8d41ed83faa177e412f89bc5600a7462a014
 F src/where.c 9ad3dea8003a8913da6a4ca8322e2fe30773f46e88a0d4fbf9db13bdb999efa2
@@ -2239,9 +2239,11 @@ F tool/version-info.c 3b36468a90faf1bbd59c65fd0eb66522d9f941eedd364fabccd7227350
 F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
 F tool/warnings.sh 49a486c5069de041aedcbde4de178293e0463ae9918ecad7539eedf0ec77a139
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P ec5d7025cba9f4acaea984d5ec29b05b7f4b01f0e36e5287f27a16895ec42bf7
-Q +0812161025272851af6233f183a6abdee5c583decc688c4763965b50e7ab1b9d
-R ac7f60236956711da3dda510a4e7ac18
+P b1e8046859bac7dc050884b33b84390f1e7cf38501ac4dd82eab4d91dafa446a
+R 5e9daa31e1154de1e8d75efa71c5c4af
+T *branch * bedrock-bighash
+T *sym-bedrock-bighash *
+T -sym-bedrock *
 U dan
-Z 9f1cd023d68cb4681e5eac7887acf1b8
+Z 6bc110f2c341d553ff1cb8338450593e
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 03a1c7c151..4e06cbf622 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-b1e8046859bac7dc050884b33b84390f1e7cf38501ac4dd82eab4d91dafa446a
+0cb853ea1dece578ae8f336c7d003e618d94ba003e25e5f5f307d7424f31b53f
diff --git a/src/wal.c b/src/wal.c
index fc0a24510f..aa55d0525f 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -458,8 +458,13 @@ int sqlite3WalTrace = 0;
 ** version-2 ("journal_mode=wal2"). Legacy clients may support version-1
 ** only.
 */
-#define WAL_VERSION1 3007000      /* For "journal_mode=wal" */
-#define WAL_VERSION2 3021000      /* For "journal_mode=wal2" */
+#ifdef SQLITE_WAL_BIGHASH
+# define WAL_VERSION1 3007001      /* For "journal_mode=wal" */
+# define WAL_VERSION2 3021001      /* For "journal_mode=wal2" */
+#else
+# define WAL_VERSION1 3007000      /* For "journal_mode=wal" */
+# define WAL_VERSION2 3021000      /* For "journal_mode=wal2" */
+#endif
 
 
 /*
@@ -831,7 +836,11 @@ struct Wal {
 ** Each page of the wal-index mapping contains a hash-table made up of
 ** an array of HASHTABLE_NSLOT elements of the following type.
 */
-typedef u16 ht_slot;
+#ifdef SQLITE_WAL_BIGHASH
+ typedef u32 ht_slot;
+#else
+ typedef u16 ht_slot;
+#endif
 
 /*
 ** This structure is used to implement an iterator that loops through
@@ -868,9 +877,14 @@ struct WalIterator {
 ** Changing any of these constants will alter the wal-index format and
 ** create incompatibilities.
 */
-#define HASHTABLE_NPAGE      4096                 /* Must be power of 2 */
-#define HASHTABLE_HASH_1     383                  /* Should be prime */
-#define HASHTABLE_NSLOT      (HASHTABLE_NPAGE*2)  /* Must be a power of 2 */
+#ifdef SQLITE_WAL_BIGHASH
+# define HASHTABLE_BITS       17                   /* 128K frames per hash */
+#else
+# define HASHTABLE_BITS       12                   /* 4K frames per hash */
+#endif
+# define HASHTABLE_NPAGE      (1<<HASHTABLE_BITS)  /* Must be power of 2 */
+# define HASHTABLE_HASH_1     383                  /* Should be prime */
+# define HASHTABLE_NSLOT      (HASHTABLE_NPAGE*2)  /* Must be a power of 2 */
 
 /*
 ** The block of page numbers associated with the first hash-table in a
@@ -2145,11 +2159,13 @@ int sqlite3WalOpen(
   assert(    40 ==  sizeof(WalCkptInfo)  );
   assert(   120 ==  WALINDEX_LOCK_OFFSET );
   assert(   136 ==  WALINDEX_HDR_SIZE    );
+#ifndef SQLITE_WAL_BIGHASH
   assert(  4096 ==  HASHTABLE_NPAGE      );
   assert(  4062 ==  HASHTABLE_NPAGE_ONE  );
   assert(  8192 ==  HASHTABLE_NSLOT      );
   assert(   383 ==  HASHTABLE_HASH_1     );
   assert( 32768 ==  WALINDEX_PGSZ        );
+#endif
   assert(     8 ==  SQLITE_SHM_NLOCK     );
   assert(     5 ==  WAL_NREADER          );
   assert(    24 ==  WAL_FRAME_HDRSIZE    );
@@ -2364,7 +2380,7 @@ static void walMergesort(
   ht_slot *aMerge = 0;            /* List to be merged */
   int iList;                      /* Index into input list */
   u32 iSub = 0;                   /* Index into aSub array */
-  struct Sublist aSub[13];        /* Array of sub-lists */
+  struct Sublist aSub[HASHTABLE_BITS+1];    /* Array of sub-lists */
 
   memset(aSub, 0, sizeof(aSub));
   assert( nList<=HASHTABLE_NPAGE && nList>0 );
-- 
2.47.2