Updates to comments describing the changeset and patchset formats.

FossilOrigin-Name: 5342f721e878b52f207731ea57411f3669ae3f3f

ext/session/sqlite3session.c

@@ -159,7 +159,7 @@ struct SessionTable {
 ** Each group of changes begins with a table header:
 **
 **   1 byte: Constant 0x54 (capital 'T')
-**   Varint: Big-endian integer set to the number of columns in the table.
+**   Varint: Number of columns in the table.
 **   nCol bytes: 0x01 for PK columns, 0x00 otherwise.
 **   N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
 **
@@ -170,16 +170,38 @@ struct SessionTable {
 **   old.* record: (delete and update only)
 **   new.* record: (insert and update only)
 **
+** The "old.*" and "new.*" records, if present, are N field records in the
+** format described above under "RECORD FORMAT", where N is the number of
+** columns in the table. The i'th field of each record is associated with
+** the i'th column of the table, counting from left to right in the order
+** in which columns were declared in the CREATE TABLE statement.
+**
+** The new.* record that is part of each INSERT change contains the values
+** that make up the new row. Similarly, the old.* record that is part of each
+** DELETE change contains the values that made up the row that was deleted 
+** from the database. In the changeset format, the records that are part
+** of INSERT or DELETE changes never contain any undefined (type byte 0x00)
+** fields.
+**
+** Within the old.* record associated with an UPDATE change, all fields
+** associated with table columns that are not PRIMARY KEY columns and are
+** not modified by the UPDATE change are set to "undefined". Other fields
+** are set to the values that made up the row before the UPDATE that the
+** change records took place. Within the new.* record, fields associated 
+** with table columns modified by the UPDATE change contain the new 
+** values. Fields associated with table columns that are not modified
+** are set to "undefined".
+**
 ** PATCHSET FORMAT:
 **
 ** A patchset is also a collection of changes. It is similar to a changeset,
-** but omits those fields that are not useful if no conflict resolution
+** but leaves undefined those fields that are not useful if no conflict
-** is required when applying the changeset.
+** resolution is required when applying the changeset.
 **
 ** Each group of changes begins with a table header:
 **
 **   1 byte: Constant 0x50 (capital 'P')
-**   Varint: Big-endian integer set to the number of columns in the table.
+**   Varint: Number of columns in the table.
 **   nCol bytes: 0x01 for PK columns, 0x00 otherwise.
 **   N bytes: Unqualified table name (encoded using UTF-8). Nul-terminated.
 **
@@ -187,7 +209,26 @@ struct SessionTable {
 **
 **   1 byte: Either SQLITE_INSERT, UPDATE or DELETE.
 **   1 byte: The "indirect-change" flag.
-**   single record: (PK fields for DELETE, or full record for INSERT/UPDATE).
+**   single record: (PK fields for DELETE, PK and modified fields for UPDATE,
+**                   full record for INSERT).
+**
+** As in the changeset format, each field of the single record that is part
+** of a patchset change is associated with the correspondingly positioned
+** table column, counting from left to right within the CREATE TABLE 
+** statement.
+**
+** For a DELETE change, all fields within the record except those associated
+** with PRIMARY KEY columns are set to "undefined". The PRIMARY KEY fields
+** contain the values identifying the row to delete.
+**
+** For an UPDATE change, all fields except those associated with PRIMARY KEY
+** columns and columns that are modified by the UPDATE are set to "undefined".
+** PRIMARY KEY fields contain the values identifying the table row to update,
+** and fields associated with modified columns contain the new column values.
+**
+** The records associated with INSERT changes are in the same format as for
+** changesets. It is not possible for a record associated with an INSERT
+** change to contain a field set to "undefined".
 */
 
 /*

manifest

@@ -1,5 +1,5 @@
-C Fix\sproblems\sin\sthe\ssessions\smodule\scausing\sit\sto\sproduce\sspurious\sSQLITE_NOMEM\serrors\swhen\shandling\sSQL\stext\sor\sblob\svalues\szero\sbytes\sin\ssize.
+C Updates\sto\scomments\sdescribing\sthe\schangeset\sand\spatchset\sformats.
-D 2015-04-08T16:43:31.690
+D 2015-04-09T19:19:22.574
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 3083cf0c2bc6618e532b9478ce735bb512322985
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -160,7 +160,7 @@ F ext/session/sessionB.test 06961b7c3641151f5d23088250ecad132501113c
 F ext/session/sessionC.test 3982f8577b0744c5ce3aaef7cfeb5bd903f17fe4
 F ext/session/session_common.tcl 9de0451b6a47218fc16b9ed8876b6238a0a3d88d
 F ext/session/sessionfault.test bef044d0952c0d62c31c8d2400be72c8684545cc
-F ext/session/sqlite3session.c 7c6516f0342772441bcd2d845760902cfc0b39b8
+F ext/session/sqlite3session.c 27eb71e164a8e05d344c6254e8f906f093dfd4d1
 F ext/session/sqlite3session.h 16608d29879a0ed3c6be6b7fb18dcdb5c707aaef
 F ext/session/test_session.c a28352e99bc6a83b94e4cce99a7bf25c73d6d489
 F ext/userauth/sqlite3userauth.h 19cb6f0e31316d0ee4afdfb7a85ef9da3333a220
@@ -1267,7 +1267,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P aeca95ac77f6f320a916f7e3c5a7a588ef4a20c8
+P b9459d5980c6249a5c1bc5ea72cb4f3b1ba0e433
-R 2b6c500da0e9b0a3fd57accc4dad1058
+R a602d0c91e77a7e6222a205b1b755ccf
 U dan
-Z aded3edd721aa55f05087866d9fe12cb
+Z 08fe7407f1e8070b595e48c16318a0a6

manifest.uuid

@@ -1 +1 @@
-b9459d5980c6249a5c1bc5ea72cb4f3b1ba0e433
+5342f721e878b52f207731ea57411f3669ae3f3f