Implement FROM-clause subqueries as co-routines whenever they are guaranteed
to be the outer-most loop of the join. FossilOrigin-Name: c7bae50bdccb5bcf3bc22e8ac5bb6725ef13db39
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drh
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manifest
14
manifest
@ -1,5 +1,5 @@
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C More\stest-case\schanges\sso\sthat\severything\sworks\swhen\sthe\sreserved_bytes\nvalue\sin\sthe\sheader\sis\snon-zero.
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D 2016-03-15T12:37:08.820
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C Implement\sFROM-clause\ssubqueries\sas\sco-routines\swhenever\sthey\sare\sguaranteed\nto\sbe\sthe\souter-most\sloop\sof\sthe\sjoin.
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D 2016-03-15T17:52:12.224
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F Makefile.in f53429fb2f313c099283659d0df6f20f932c861f
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F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
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F Makefile.msc df0bf9ff7f8b3f4dd9fb4cc43f92fe58f6ec5c66
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@ -350,7 +350,7 @@ F src/printf.c 63e6fb12bbe702dd664dc3703776c090383a5a26
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F src/random.c ba2679f80ec82c4190062d756f22d0c358180696
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F src/resolve.c b8f7174e5f8c33c44ded3a25a973d0bb89228c20
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F src/rowset.c 9fe4b3ad7cc00944386bb600233d8f523de07a6e
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F src/select.c 137b31daa84d57d67847bf621bb54f3353e2077b
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F src/select.c 6dd2097bb158efe3b8d68683dcc3b4a49e907a34
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F src/shell.c 5e0ab1e708dc294330ccd8230536e1801f60822e
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F src/sqlite.h.in 0235586b3fb639e85998d495c90f007657fd82af
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F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
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@ -999,7 +999,7 @@ F test/securedel2.test 2d54c28e46eb1fd6902089958b20b1b056c6f1c5
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F test/select1.test be62204d2bd9a5a8a149e9974cfddce893d8f686
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F test/select2.test 352480e0e9c66eda9c3044e412abdf5be0215b56
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F test/select3.test 2ce595f8fb8e2ac10071d3b4e424cadd4634a054
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F test/select4.test 453631158540e5f685b81cac5b7e8bd8c6b4c5fc
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F test/select4.test d926792a5e4d88fef0ddcddeb45d27ce75f7296c
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F test/select5.test e758b8ef94f69b111df4cb819008856655dcd535
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F test/select6.test 39eac4a5c03650b2b473c532882273283ee8b7a0
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F test/select7.test 95e370c42d47c3c52377d05e9ffc01ccff7c1f61
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@ -1456,7 +1456,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
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F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
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F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
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P 051c61ebae921b70f843c55aacf046a9922cc187
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R 1b522ee9926e242e3422d1eddaaf0fbf
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P 2fd095b14b03a508169bba710d2e8e2addf4b8f5
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R dae03fc18d1aaaa839efcf6d42490a7e
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U drh
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Z 3fc58440746cd83f06c07d7c16cdd74a
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Z 042547ad8e59422492ad781582901ed5
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@ -1 +1 @@
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2fd095b14b03a508169bba710d2e8e2addf4b8f5
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c7bae50bdccb5bcf3bc22e8ac5bb6725ef13db39
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20
src/select.c
20
src/select.c
@ -4970,10 +4970,24 @@ int sqlite3Select(
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}
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/* Generate code to implement the subquery
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**
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** The subquery is implemented as a co-routine if all of these are true:
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** (1) The subquery is guaranteed to be the outer loop (so that it
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** does not need to be computed more than once)
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** (2) The ALL keyword after SELECT is omitted. (Applications are
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** allowed to say "SELECT ALL" instead of just "SELECT" to disable
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** the use of co-routines.)
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** (3) Co-routines are not disabled using sqlite3_test_control()
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** with SQLITE_TESTCTRL_OPTIMIZATIONS.
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**
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** TODO: Are there other reasons beside (1) to use a co-routine
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** implementation?
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*/
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if( pTabList->nSrc==1
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&& (p->selFlags & SF_All)==0
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&& OptimizationEnabled(db, SQLITE_SubqCoroutine)
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if( i==0
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&& (pTabList->nSrc==1
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|| (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0) /* (1) */
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&& (p->selFlags & SF_All)==0 /* (2) */
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&& OptimizationEnabled(db, SQLITE_SubqCoroutine) /* (3) */
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){
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/* Implement a co-routine that will return a single row of the result
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** set on each invocation.
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@ -12,7 +12,6 @@
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# focus of this file is testing UNION, INTERSECT and EXCEPT operators
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# in SELECT statements.
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#
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# $Id: select4.test,v 1.30 2009/04/16 00:24:24 drh Exp $
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set testdir [file dirname $argv0]
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source $testdir/tester.tcl
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@ -936,4 +935,40 @@ do_execsql_test select4-15.1 {
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ORDER BY 1;
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} {1 33 456 2 33 789}
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# Enhancement (2016-03-15): Use a co-routine for subqueries if the
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# subquery is guaranteed to be the outer-most query
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#
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do_execsql_test select4-16.1 {
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DROP TABLE IF EXISTS t1;
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CREATE TABLE t1(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,
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PRIMARY KEY(a,b DESC)) WITHOUT ROWID;
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WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<100)
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INSERT INTO t1(a,b,c,d)
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SELECT x%10, x/10, x, printf('xyz%dabc',x) FROM c;
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SELECT t3.c FROM
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(SELECT a,max(b) AS m FROM t1 WHERE a>=5 GROUP BY a) AS t2
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JOIN t1 AS t3
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WHERE t2.a=t3.a AND t2.m=t3.b
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ORDER BY t3.a;
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} {95 96 97 98 99}
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do_execsql_test select4-16.2 {
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SELECT t3.c FROM
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(SELECT a,max(b) AS m FROM t1 WHERE a>=5 GROUP BY a) AS t2
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CROSS JOIN t1 AS t3
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WHERE t2.a=t3.a AND t2.m=t3.b
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ORDER BY t3.a;
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} {95 96 97 98 99}
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do_execsql_test select4-16.3 {
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SELECT t3.c FROM
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(SELECT a,max(b) AS m FROM t1 WHERE a>=5 GROUP BY a) AS t2
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LEFT JOIN t1 AS t3
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WHERE t2.a=t3.a AND t2.m=t3.b
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ORDER BY t3.a;
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} {95 96 97 98 99}
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finish_test
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