From: drh <>
Date: Fri, 31 May 2024 14:39:42 +0000 (+0000)
Subject: Document the OP_Explain opcode.  Add the WhereLoop.rRun value as P3 in
X-Git-Tag: version-3.47.0~364
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d72ca8f810a0159d87cc16321a8d974373eceab3;p=thirdparty%2Fsqlite.git

Document the OP_Explain opcode.  Add the WhereLoop.rRun value as P3 in
OP_Explain opcodes associated with WhereLoops, for testing purposes.

FossilOrigin-Name: 996c46e61d9a53a54018672dd407b8ba8c480dd6795393428f9d5fcb81b47ab5
---

diff --git a/manifest b/manifest
index f722e3deb9..c7aef4ab52 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Back\sout\s[dcc2bb2c562e97e090174],\sas\sit\sbreaks\sthe\s--with-wasi-sdk\sbuilds.
-D 2024-05-30T21:54:16.706
+C Document\sthe\sOP_Explain\sopcode.\s\sAdd\sthe\sWhereLoop.rRun\svalue\sas\sP3\sin\nOP_Explain\sopcodes\sassociated\swith\sWhereLoops,\sfor\stesting\spurposes.
+D 2024-05-31T14:39:42.881
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -825,7 +825,7 @@ F src/upsert.c 2e60567a0e9e8520c18671b30712a88dc73534474304af94f32bb5f3ef65ac65
 F src/utf.c f23165685a67b4caf8ec08fb274cb3f319103decfb2a980b7cfd55d18dfa855e
 F src/util.c 4d6d7ebfe6772a1b950c97bbb1d1a72ad4874617ec498ab8aa73b7f5a43e44bb
 F src/vacuum.c 604fcdaebe76f3497c855afcbf91b8fa5046b32de3045bab89cc008d68e40104
-F src/vdbe.c 2448b34ff095efa5a8d9dd525c4c0842ef7226e44b68fe8df1053ee9894aa5fd
+F src/vdbe.c b05777c3ff2ed7b9dfc347e7cdee18e371aa6811cef1fe83454691b0dbe2cc9f
 F src/vdbe.h c2d78d15112c3fc5ab87f5e8e0b75d2db1c624409de2e858c3d1aafb1650bb4f
 F src/vdbeInt.h 949669dfd8a41550d27dcb905b494f2ccde9a2e6c1b0b04daa1227e2e74c2b2c
 F src/vdbeapi.c 80235ac380e9467fec1cb0883354d841f2a771976e766995f7e0c77f845406df
@@ -840,9 +840,9 @@ F src/vxworks.h d2988f4e5a61a4dfe82c6524dd3d6e4f2ce3cdb9
 F src/wal.c 887fc4ca3f020ebb2e376f222069570834ac63bf50111ef0cbf3ae417048ed89
 F src/wal.h ba252daaa94f889f4b2c17c027e823d9be47ce39da1d3799886bbd51f0490452
 F src/walker.c 7c7ea0115345851c3da4e04e2e239a29983b61fb5b038b94eede6aba462640e2
-F src/where.c 5ddff7d4e0c0f7a2616efc126e4b8224387ce5fa4f5adf0737c8daa3e83824cf
+F src/where.c 301bedd98cf76463fd57081881607943442bfbba213a58240f7981dec5a160cf
 F src/whereInt.h 002adc3aa2cc10733b9b27958fdbe893987cd989fab25a9853941c1f9b9b0a65
-F src/wherecode.c d5184620bcb5265d59072cb66e1386bfe0331a9ce7614286f9ab79a4fcd00fb8
+F src/wherecode.c 5ad509221ebb4d3b35a8a6ef361f2c5b54129b8c273aa434dd3053d2e25d1794
 F src/whereexpr.c 67d15caf88a1a9528283d68ff578e024cf9fe810b517bb0343e5aaf695ad97dd
 F src/window.c 5d95122dd330bfaebd732358c8ef067c5a9394a53ac249470d611d0ce2c52be2
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@@ -2194,8 +2194,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P dcc2bb2c562e97e090174d4d0970bfa1551e5eb4db022e6d232c4dd786818e45
-R 26b2d1af00d15dbbae9294d17198b2cc
-U stephan
-Z 5e10d8a42e727262c6d109f98d1a95c0
+P 62199562c26f77d059aa0bbda42a421a7aece828aa94d14a40c701a6384d1cf6
+R 85967a315d01ec0513367341097e62e2
+U drh
+Z b127a4b9aa205bcbd712a7eda1be0138
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index bcca3c37fe..5d06e47e84 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-62199562c26f77d059aa0bbda42a421a7aece828aa94d14a40c701a6384d1cf6
\ No newline at end of file
+996c46e61d9a53a54018672dd407b8ba8c480dd6795393428f9d5fcb81b47ab5
\ No newline at end of file
diff --git a/src/vdbe.c b/src/vdbe.c
index 6bfcb0ee19..28f12e0542 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -9015,14 +9015,29 @@ case OP_ReleaseReg: {
 
 /* Opcode: Noop * * * * *
 **
-** Do nothing.  This instruction is often useful as a jump
-** destination.
+** Do nothing.  Continue downward to the next opcode.
 */
-/*
-** The magic Explain opcode are only inserted when explain==2 (which
-** is to say when the EXPLAIN QUERY PLAN syntax is used.)
-** This opcode records information from the optimizer.  It is the
-** the same as a no-op.  This opcodesnever appears in a real VM program.
+/* Opcode: Explain P1 P2 P3 P4 *
+**
+** This is the same as OP_Noop during normal query execution.  The
+** purpose of this opcode is to hold information about the query
+** plan for the purpose of EXPLAIN QUERY PLAN output.
+**
+** The P4 value is human-readable text that describes the query plan
+** element.  Something like "SCAN t1" or "SEARCH t2 USING INDEX t2x1".
+**
+** The P1 value is the ID of the current element and P2 is the parent
+** element for the case of nested query plan elements.  If P2 is zero
+** then this element is a top-level element.
+**
+** For loop elements, P3 is the estimated code of each invocation of this
+** element.
+**
+** As with all opcodes, the meanings of the parameters for OP_Explain
+** are subject to change from one release to the next.  Applications
+** should not attempt to interpret or use any of the information
+** contined in the OP_Explain opcode.  The information provided by this
+** opcode is intended for testing and debugging use only.
 */
 default: {          /* This is really OP_Noop, OP_Explain */
   assert( pOp->opcode==OP_Noop || pOp->opcode==OP_Explain );
diff --git a/src/where.c b/src/where.c
index ed095fa3b0..64bda2327f 100644
--- a/src/where.c
+++ b/src/where.c
@@ -5262,7 +5262,7 @@ static LogEst whereSortingCost(
 ** smaller tables.  The central table is called the "fact" table.
 ** The smaller tables that get joined are "dimension tables".
 **
-** SIDE EFFECT:
+** SIDE EFFECT:  (and really the whole point of this subroutine)
 **
 ** If pWInfo describes a star-query, then the cost on WhereLoops for the
 ** fact table is reduced.  This heuristic helps keep fact tables in
diff --git a/src/wherecode.c b/src/wherecode.c
index 30624be8a2..80fbbfac4c 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -218,7 +218,8 @@ int sqlite3WhereExplainOneScan(
     zMsg = sqlite3StrAccumFinish(&str);
     sqlite3ExplainBreakpoint("",zMsg);
     ret = sqlite3VdbeAddOp4(v, OP_Explain, sqlite3VdbeCurrentAddr(v),
-                            pParse->addrExplain, 0, zMsg,P4_DYNAMIC);
+                            pParse->addrExplain, pLoop->rRun,
+                            zMsg, P4_DYNAMIC);
   }
   return ret;
 }