sqlite3_snapshot_get

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References

int sqlite3_snapshot_get  
(  
    sqlite3 * db,  
    const char * zSchema,  
    sqlite3_snapshot ** ppSnapshot  
)  
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int sqlite3_snapshot_get (     sqlite3 * db,     const char * zSchema,     sqlite3_snapshot ** ppSnapshot )

Remarks

CAPI3REF: Record A Database Snapshot CONSTRUCTOR: sqlite3_snapshot

^The [sqlite3_snapshot_get(D,S,P)] interface attempts to make a new [sqlite3_snapshot] object that records the current state of schema S in database connection D. ^On success, the [sqlite3_snapshot_get(D,S,P)] interface writes a pointer to the newly created [sqlite3_snapshot] object into *P and returns SQLITE_OK. If there is not already a read-transaction open on schema S when this function is called, one is opened automatically.

The following must be true for this function to succeed. If any of the following statements are false when sqlite3_snapshot_get() is called, SQLITE_ERROR is returned. The final value of *P is undefined in this case.

• The database handle must not be in [autocommit mode].

• Schema S of [database connection] D must be a [WAL mode] database.

• There must not be a write transaction open on schema S of database connection D.

• One or more transactions must have been written to the current wal file since it was created on disk (by any connection). This means that a snapshot cannot be taken on a wal mode database with no wal file immediately after it is first opened. At least one transaction must be written to it first.

This function may also return SQLITE_NOMEM. If it is called with the database handle in autocommit mode but fails for some other reason, whether or not a read transaction is opened on schema S is undefined.

The [sqlite3_snapshot] object returned from a successful call to [sqlite3_snapshot_get()] must be freed using [sqlite3_snapshot_free()] to avoid a memory leak.

The [sqlite3_snapshot_get()] interface is only available when the [SQLITE_ENABLE_SNAPSHOT] compile-time option is used.