Expand on the comment above OP_Destroy to explain why it throws an error if

there are any active reader VMs.

FossilOrigin-Name: b9a8c2b9bec9f537b2d5aff6659a5748b1f70b53519a1f9dfceb5209154eca8e

diff --git a/manifest b/manifest
index e10ca39c0b426180f1279bda2bb629e21986d8e3..e3f79625e85cd228906cd319bed265c811f61e8c 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Have\sthe\srtree\smodule\sclose\sany\sopen\sblob-handle\swithin\sthe\sxSavepoint\smethod.\nThis\sprevents\ssuch\san\sopen\sblob\shandle\sfrom\sinterfering\swith\sDROP\sTABLE\noperations.
-D 2017-04-08T13:52:41.332
+C Expand\son\sthe\scomment\sabove\sOP_Destroy\sto\sexplain\swhy\sit\sthrows\san\serror\sif\nthere\sare\sany\sactive\sreader\sVMs.
+D 2017-04-08T14:11:47.626
 F Makefile.in 1cc758ce3374a32425e4d130c2fe7b026b20de5b8843243de75f087c0a2661fb
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc a4c0613a18663bda56d8cf76079ab6590a7c3602e54befb4bbdef76bcaa38b6a
@@ -468,7 +468,7 @@ F src/update.c 456d4a4656f8a03c2abc88a51b19172197400e58
 F src/utf.c 699001c79f28e48e9bcdf8a463da029ea660540c
 F src/util.c ca8440ede81e155d15cff7c101654f60b55a9ae6
 F src/vacuum.c 1fe4555cd8c9b263afb85b5b4ee3a4a4181ad569
-F src/vdbe.c b070c9c81a5faff5d9fc9563c7c030e3e1adb69d835259470fd945ef61f3f9fb
+F src/vdbe.c 808fda3d50f544120d27c731449b524b4ec8f8b0f734b228831078f0ba53ecb9
 F src/vdbe.h caa5346d52bae2a3c8c1dcfa60a7a4dc878a9e3865cb8239da55808b316c8158
 F src/vdbeInt.h 5db089ce18c4feff8820ec6e4cac2d2c82e03d4b1d96f10a6e43832147b8dffe
 F src/vdbeapi.c 5b08d82592bcff4470601fe78aaabebd50837860
@@ -1570,7 +1570,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 78c1e90305d48917d9423d8e50a7dfd15ec27aa93cb421610062229c7ede13a6
-R 0c38afb8d28742bfd99c862428490c09
+P fa4416adc2a9a3a80db1d5befc0b95c3d0fc41affe38f7f2f45cdfae3f1b49eb
+R a9817579cdde3e2d07834f7afee2d7a0
 U dan
-Z 475b2e97335280e83d36c7e778a71dcc
+Z aefe60bc1892ed67bf5beab6d8c742fc

diff --git a/manifest.uuid b/manifest.uuid
index c1e1fd932b1996d109673202fddecb3c730cd83a..737a0a72a7d20054031fcfabbff9acdca47ad799 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fa4416adc2a9a3a80db1d5befc0b95c3d0fc41affe38f7f2f45cdfae3f1b49eb
\ No newline at end of file
+b9a8c2b9bec9f537b2d5aff6659a5748b1f70b53519a1f9dfceb5209154eca8e
\ No newline at end of file

diff --git a/src/vdbe.c b/src/vdbe.c
index 51c702a4adc635b21193b9eabcb9e68b4d9c3687..a990afb11d148b6657401923f19d49b991729bad 100644 (file)
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -5386,10 +5386,17 @@ case OP_IdxGE:  {       /* jump */
 ** might be moved into the newly deleted root page in order to keep all
 ** root pages contiguous at the beginning of the database.  The former
 ** value of the root page that moved - its value before the move occurred -
-** is stored in register P2.  If no page 
-** movement was required (because the table being dropped was already 
-** the last one in the database) then a zero is stored in register P2.
-** If AUTOVACUUM is disabled then a zero is stored in register P2.
+** is stored in register P2. If no page movement was required (because the
+** table being dropped was already the last one in the database) then a 
+** zero is stored in register P2.  If AUTOVACUUM is disabled then a zero 
+** is stored in register P2.
+**
+** This opcode throws an error if there are any active reader VMs when
+** it is invoked. This is done to avoid the difficulty associated with 
+** updating existing cursors when a root page is moved in an AUTOVACUUM 
+** database. This error is thrown even if the database is not an AUTOVACUUM 
+** db in order to avoid introducing an incompatibility between autovacuum 
+** and non-autovacuum modes.
 **
 ** See also: Clear
 */