NAME

sqlite3_snapshot_get — record a database snapshot

SYNOPSIS

#include <sqlite3.h>

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

DESCRIPTION

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.

IMPLEMENTATION NOTES

These declarations were extracted from the interface documentation at line 10470.

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

SEE ALSO

sqlite3(3), sqlite3_get_autocommit(3), sqlite3_snapshot(3), sqlite3_snapshot_free(3)