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Add documentation for sqlite3changeset_concat() to sqlite3session.h.

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FossilOrigin-Name: ada9efa53a6ea55f89d237cfd530f1d180343e19
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dan
2011-04-15 12:04:50 +00:00
parent 6cda207f5f
commit 29e03e977c
3 changed files with 83 additions and 11 deletions
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80
ext/session/sqlite3session.h
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@ -523,12 +523,84 @@ int sqlite3changeset_invert(
);
/*
** CAPI3REF: Combine Two Changeset Objects
** CAPI3REF: Concatenate Two Changeset Objects
**
** This function is used to concatenate two changesets, A and B, into a
** single changeset. The result is a changeset equivalent to applying
** changeset A followed by changeset B.
**
** Rows are identified by the values in their PRIMARY KEY columns. A change
** in changeset A is considered to apply to the same row as a change in
** changeset B if the two rows have the same primary key.
**
** Changes to rows that appear only in changeset A or B are copied into the
** output changeset. Or, if both changeset A and B contain a change that
** applies to a single row, the output 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">Change A </th>
** <th style="white-space:pre">Change B </th>
** <th>Output Change
** <tr><td>INSERT <td>INSERT <td>
** Change A is copied into the output changeset. Change B is discarded.
** This case does not occur if changeset B is recorded immediately after
** changeset A.
** <tr><td>INSERT <td>UPDATE <td>
** An INSERT change is copied into the output changeset. The values in
** the INSERT change are as if the row was inserted by change A and then
** updated according to change B.
** <tr><td>INSERT <td>DELETE <td>
** No change at all is copied into the output changeset.
** <tr><td>UPDATE <td>INSERT <td>
** Change A is copied into the output changeset. Change B is discarded.
** This case does not occur if changeset B is recorded immediately after
** changeset A.
** <tr><td>UPDATE <td>UPDATE <td>
** A single UPDATE is copied into the output changeset. The accompanying
** values are as if the row was updated once by change A and then again
** by change B.
** <tr><td>UPDATE <td>DELETE <td>
** A single DELETE is copied into the output changeset.
** <tr><td>DELETE <td>INSERT <td>
** If one or more of the column values in the row inserted by change
** B differ from those in the row deleted by change A, an UPDATE
** change is added to the output changeset. Otherwise, if the inserted
** row is exactly the same as the deleted row, no change is added to
** the output changeset.
** <tr><td>DELETE <td>UPDATE <td>
** Change A is copied into the output changeset. Change B is discarded.
** This case does not occur if changeset B is recorded immediately after
** changeset A.
** <tr><td>DELETE <td>DELETE <td>
** Change A is copied into the output changeset. Change B is discarded.
** This case does not occur if changeset B is recorded immediately after
** changeset A.
** </table>
**
** If the two changesets contain changes to the same table, then the number
** of columns and the position of the primary key columns for the table must
** be the same in each changeset. If this is not the case, attempting to
** concatenate the two changesets together fails and this function returns
** SQLITE_SCHEMA. If either of the two input changesets appear 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.
**
** If none of the above errors occur, SQLITE_OK is returned and *ppOut set
** to point to a buffer containing the output changeset. It is the
** responsibility of the caller to eventually call sqlite3_free() on *ppOut
** to release memory allocated for the buffer. *pnOut is set to the number
** of bytes in the output changeset. If an error does occur, both *ppOut and
** *pnOut are set to zero before returning.
*/
int sqlite3changeset_concat(
int nLeft, void *pLeft, /* First input changeset */
int nRight, void *Right, /* Second input changeset */
int *pnOut, void **ppOut /* OUT: Output changeset */
int nA, /* Number of bytes in buffer pA */
void *pA, /* Pointer to buffer containing changeset A */
int nB, /* Number of bytes in buffer pB */
void *pB, /* Pointer to buffer containing changeset B */
int *pnOut, /* OUT: Number of bytes in output changeset */
void **ppOut /* OUT: Buffer containing output changeset */
);
/*