Note in the documentation that when iterating through a changeset, all changes to a single table are grouped together. Also add the sqlite3session_isempty() function.

FossilOrigin-Name: 364f3b820a26f9b15cf74a0222ed5e302becc54f

ext/session/session1.test

@@ -464,6 +464,33 @@ do_iterator_test 7.1 * {
   {INSERT t1 0 X. {} {t one i 1}}
 }
 
+#-------------------------------------------------------------------------
+# Test the sqlite3session_isempty() function.
+#
+do_test 8.1 {
+  execsql {
+    CREATE TABLE t5(x PRIMARY KEY, y);
+    CREATE TABLE t6(x PRIMARY KEY, y);
+    INSERT INTO t5 VALUES('a', 'b');
+    INSERT INTO t6 VALUES('a', 'b');
+  }
+  sqlite3session S db main
+  S attach *
+
+  S isempty
+} {0}
+do_test 8.2 {
+  execsql { DELETE FROM t5 }
+  S isempty
+} {1}
+do_test 8.3 {
+  S delete
+  sqlite3session S db main
+  S attach t5
+  execsql { DELETE FROM t5 }
+  S isempty
+} {0}
+do_test 8.4 { S delete } {}
 
 catch { db2 close }
 finish_test

ext/session/sqlite3session.c

@@ -1773,6 +1773,23 @@ int sqlite3session_indirect(sqlite3_session *pSession, int bIndirect){
   return ret;
 }
 
+/*
+** Return true if there have been no changes to monitored tables recorded
+** by the session object passed as the only argument.
+*/
+int sqlite3session_isempty(sqlite3_session *pSession){
+  int ret = 0;
+  SessionTable *pTab;
+
+  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));
+  for(pTab=pSession->pTable; pTab && ret==0; pTab=pTab->pNext){
+    ret = (pTab->nEntry>0);
+  }
+  sqlite3_mutex_leave(sqlite3_db_mutex(pSession->db));
+
+  return ret;
+}
+
 /*
 ** Create an iterator used to iterate through the contents of a changeset.
 */

ext/session/sqlite3session.h

@@ -254,6 +254,23 @@ int sqlite3session_changeset(
   void **ppChangeset              /* OUT: Buffer containing changeset */
 );
 
+/*
+** CAPI3REF: Test if a changeset has recorded any changes.
+**
+** Return non-zero if no changes to attached tables have been recorded by 
+** the session object passed as the first argument. Otherwise, if one or 
+** more changes have been recorded, return zero.
+**
+** Even if this function returns zero, it is possible that calling
+** [sqlite3session_changeset()] on the session handle may still return a
+** changeset that contains no changes. This can happen when a row in 
+** an attached table is modified and then later on the original values 
+** are restored. However, if this function returns non-zero, then it is
+** guaranteed that a call to sqlite3session_changeset() will return a 
+** changeset containing zero changes.
+*/
+int sqlite3session_isempty(sqlite3_session *pSession);
+
 /*
 ** CAPI3REF: Create An Iterator To Traverse A Changeset 
 **
@@ -276,6 +293,15 @@ int sqlite3session_changeset(
 ** by passing it to [sqlite3changeset_finalize()]. The buffer containing the
 ** changeset (pChangeset) must remain valid until after the iterator is
 ** destroyed.
+**
+** Assuming the changeset blob was created by one of the
+** [sqlite3session_changeset()], [sqlite3changeset_concat()] or
+** [sqlite3changest_invert()], all changes within the changeset that apply
+** to a single table are grouped together. This means that when an application
+** iterates through a changeset using an iterator created by this function,
+** all changes that relate to a single table are visted consecutively. There 
+** is no chance that the iterator will visit a change the applies to table X, 
+** then one for table Y, and then later on visit another change for table X.
 */
 int sqlite3changeset_start(
   sqlite3_changeset_iter **pp,    /* OUT: New changeset iterator handle */

ext/session/test_session.c

@@ -38,6 +38,7 @@ static int test_session_cmd(
     { "delete",    0, "",      }, /* 2 */
     { "enable",    1, "BOOL",  }, /* 3 */
     { "indirect",  1, "BOOL",  }, /* 4 */
+    { "isempty",   0, "",      }, /* 5 */
     { 0 }
   };
   int iSub;
@@ -99,6 +100,13 @@ static int test_session_cmd(
       Tcl_SetObjResult(interp, Tcl_NewBooleanObj(val));
       break;
     }
+
+    case 5: {      /* isempty */
+      int val;
+      val = sqlite3session_isempty(pSession);
+      Tcl_SetObjResult(interp, Tcl_NewBooleanObj(val));
+      break;
+    }
   }
 
   return TCL_OK;

manifest

@@ -1,5 +1,5 @@
-C Add\sa\sfew\scasts\srequired\sby\s64-bit\sVS2010\sto\sthe\ssessions\scode.
-D 2011-07-15T19:11:32.763
+C Note\sin\sthe\sdocumentation\sthat\swhen\siterating\sthrough\sa\schangeset,\sall\schanges\sto\sa\ssingle\stable\sare\sgrouped\stogether.\sAlso\sadd\sthe\ssqlite3session_isempty()\sfunction.
+D 2011-07-16T18:05:07.557
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in c1d7a7f4fd8da6b1815032efca950e3d5125407e
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -102,7 +102,7 @@ F ext/rtree/rtree_util.tcl 06aab2ed5b826545bf215fff90ecb9255a8647ea
 F ext/rtree/sqlite3rtree.h 1af0899c63a688e272d69d8e746f24e76f10a3f0
 F ext/rtree/tkt3363.test 142ab96eded44a3615ec79fba98c7bde7d0f96de
 F ext/rtree/viewrtree.tcl eea6224b3553599ae665b239bd827e182b466024
-F ext/session/session1.test f5d9f2e362abe2563181389509822bda956516ee
+F ext/session/session1.test 6ad289a19648890cb138e4d2c9d2f5c1f714e505
 F ext/session/session2.test 99ca0da7ddb617d42bafd83adccf99f18ae0384b
 F ext/session/session3.test a7a9ce59b8d1e49e2cc23d81421ac485be0eea01
 F ext/session/session4.test a6ed685da7a5293c5d6f99855bcf41dbc352ca84
@@ -110,9 +110,9 @@ F ext/session/session5.test 8fdfaf9dba28a2f1c6b89b06168bdab1fef2d478
 F ext/session/session6.test 443789bc2fca12e4f7075cf692c60b8a2bea1a26
 F ext/session/session_common.tcl 1539d8973b2aea0025c133eb0cc4c89fcef541a5
 F ext/session/sessionfault.test 401045278298a242cbc2e4bc986c102f01ff2180
-F ext/session/sqlite3session.c b31221e6e068476f736e8aaf5c7b66895d1b16f4
-F ext/session/sqlite3session.h f34905c818569779ddaea1bbef43469177614c69
-F ext/session/test_session.c 209f13fa8f4a597ffcc15fd0f8a3f27ed079c5e5
+F ext/session/sqlite3session.c b35e70924598794e157325eb7176523293f1d48c
+F ext/session/sqlite3session.h b977d0bae338918c64f4f18f03f4648ad91df407
+F ext/session/test_session.c ea4dc9b4a1895c8e6bddcbfe3838d7eb57df2d99
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
 F ltmain.sh 3ff0879076df340d2e23ae905484d8c15d5fdea8
 F main.mk f56d9895882f5cdd9f9f9ba8f8a679e9202288c1
@@ -961,7 +961,7 @@ F tool/symbols.sh bc2a3709940d47c8ac8e0a1fdf17ec801f015a00
 F tool/tostr.awk 11760e1b94a5d3dcd42378f3cc18544c06cfa576
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings.sh 347d974d143cf132f953b565fbc03026f19fcb4d
-P 282474c42f24f0e66c69b576b72ef8ce764d49e2
-R dce52d6dc32cededac0b5cc1823e4002
+P 5ac4a06111b5fad5f58c20ef5d2b65aeb23e105a
+R 3578d3e546ebd39820e5a49b01cb2c15
 U dan
-Z 91f64262d00fcd067a4fb1a130723392
+Z 84bc1b5f26e12cf6f38c5104884f25b6

manifest.uuid

@@ -1 +1 @@
-5ac4a06111b5fad5f58c20ef5d2b65aeb23e105a
+364f3b820a26f9b15cf74a0222ed5e302becc54f