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Updates to comments describing the changeset and patchset formats.

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FossilOrigin-Name: 5342f721e878b52f207731ea57411f3669ae3f3f
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dan
2015-04-09 19:19:22 +00:00
parent 3cc89d9567
commit 730bb805a8
3 changed files with 53 additions and 12 deletions
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51
ext/session/sqlite3session.c
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@ -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
** is required when applying the changeset.
** but leaves undefined those fields that are not useful if no conflict
** 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".
*/
/*