NAME
sqlite3changegroup_add —
Add A
Changeset To A Changegroup
SYNOPSIS
int
sqlite3changegroup_add(
sqlite3_changegroup*,
int nData,
void *pData);
DESCRIPTION
Add all changes within the changeset (or patchset) in buffer pData (size nData
bytes) to the changegroup.
If the buffer contains a patchset, then all prior calls to this function on the
same changegroup object must also have specified patchsets. Or, if the buffer
contains a changeset, so must have the earlier calls to this function.
Otherwise, SQLITE_ERROR is returned and no changes are added to the
changegroup.
Rows within the changeset and changegroup are identified by the values in their
PRIMARY KEY columns. A change in the changeset is considered to apply to the
same row as a change already present in the changegroup if the two rows have
the same primary key.
Changes to rows that do not already appear in the changegroup are simply copied
into it. Or, if both the new changeset and the changegroup contain changes
that apply to a single row, the final contents of the changegroup depends on
the type of each change, as follows:
<table border=1 style="margin-left:8ex;margin-right:8ex">
<tr><th style="white-space:pre">Existing Change
</th> <th style="white-space:pre">New Change </th>
<th>Output Change <tr><td>INSERT <td>INSERT <td>
The new change is ignored. This case does not occur if the new changeset was
recorded immediately after the changesets already added to the changegroup.
<tr><td>INSERT <td>UPDATE <td> The INSERT change
remains in the changegroup. The values in the INSERT change are modified as if
the row was inserted by the existing change and then updated according to the
new change. <tr><td>INSERT <td>DELETE <td> The
existing INSERT is removed from the changegroup. The DELETE is not added.
<tr><td>UPDATE <td>INSERT <td> The new change is
ignored. This case does not occur if the new changeset was recorded
immediately after the changesets already added to the changegroup.
<tr><td>UPDATE <td>UPDATE <td> The existing UPDATE
remains within the changegroup. It is amended so that the accompanying values
are as if the row was updated once by the existing change and then again by
the new change. <tr><td>UPDATE <td>DELETE <td> The
existing UPDATE is replaced by the new DELETE within the changegroup.
<tr><td>DELETE <td>INSERT <td> If one or more of the
column values in the row inserted by the new change differ from those in the
row deleted by the existing change, the existing DELETE is replaced by an
UPDATE within the changegroup. Otherwise, if the inserted row is exactly the
same as the deleted row, the existing DELETE is simply discarded.
<tr><td>DELETE <td>UPDATE <td> The new change is
ignored. This case does not occur if the new changeset was recorded
immediately after the changesets already added to the changegroup.
<tr><td>DELETE <td>DELETE <td> The new change is
ignored. This case does not occur if the new changeset was recorded
immediately after the changesets already added to the changegroup.
</table>
If the new changeset contains changes to a table that is already present in the
changegroup, then the number of columns and the position of the primary key
columns for the table must be consistent. If this is not the case, this
function fails with SQLITE_SCHEMA. If the input changeset appears to be
corrupt and the corruption is detected, SQLITE_CORRUPT is returned. Or, if an
out-of-memory condition occurs during processing, this function returns
SQLITE_NOMEM. In all cases, if an error occurs the final contents of the
changegroup is undefined.
If no error occurs, SQLITE_OK is returned.