created specifically for this purpose. This transaction uses the default isolation level, i.e. snapshot (concurrency), write and wait. If all goes well, the transaction is committed. Uncaught exceptions the trigger is executed, a transaction is automatically started with the default isolation level (snapshot (concurrency), write, wait) Disconnecting from a database ON DISCONNECT Before the trigger is is executed, a transaction is automatically started with the default isolation level (snapshot (concurrency), write, wait) When a transaction is started ON TRANSACTION START The trigger is executed

ISOLATION_LEVEL Уровень изоляции текущей транзакции — CURRENT_TRANSACTION. Значения: "READ_COMMITED", "SNAPSHOT" или "CONSISTENCY". LOCK_TIMEOUT Время ожидания транзакцией высвобождения ресурса при блокировке SET TRANSACTION [NAME tr_name] [READ WRITE | READ ONLY] [[ISOLATION LEVEL] { SNAPSHOT [TABLE STABILITY] | READ COMMITTED [[NO] RECORD_VERSION] }] [NO WAIT | WAIT [LOCK TIMEOUT транзакция стартует со следующими характеристиками. SET TRANSACTION READ WRITE WAIT ISOLATION LEVEL SNAPSHOT; При старте со стороны клиента любой транзакции (заданной явно или

CURRENT_ROLE� variable. ISOLATION_LEVEL The isolation level of the current transaction: 'READ COMMITTED', 'SNAPSHOT' or 'CONSISTENCY'. LOCK_TIMEOUT Lock timeout of the current transaction. Added in 2.5.3. READ_ONLY Syntax SET TRANSACTION [NAME tr_name] [READ WRITE | READ ONLY] [[ISOLATION LEVEL] { SNAPSHOT [TABLE STABILITY] | READ COMMITTED [[NO] RECORD_VERSION] }] [WAIT | NO WAIT] [LOCK TIMEOUT resolution mode and isolation level, which are: SET TRANSACTION READ WRITE WAIT ISOLATION LEVEL SNAPSHOT; The server assigns integer numbers to transactions sequentially. Whenever a client starts any

erstellten Transaktion ausgeführt. Diese Transaktion verwendet die Standardisolationsstufe, d. h. Snapshot (Parallelität), Schreiben und Warten. Wenn alles gut geht, wird die Transaktion festgeschrieben (Server)-Version. ISOLATION_LEVEL Die Isolationsstufe der aktuellen Transaktion: 'READ COMMITTED', 'SNAPSHOT' oder 'CONSISTENCY'. NETZWERK_PROTOKOLL Das für die Verbindung verwendete Protokoll: 'TCPv4', [ ...] ::= READ {ONLY | WRITE} | [NO] WAIT | [ISOLATION LEVEL] { SNAPSHOT [TABLE [STABILITY]] | READ {UNCOMMITED | COMMITTED } Chapter 12. Transaktionssteuerung

PROTECTED, READ, RESERV, RESERVING, RETAIN, SCHEMA, SEGMENT, SHADOW, SHARED, SINGULAR, SIZE, SNAPSHOT, SORT, STABILITY, STARTING, STARTS, STATEMENT, STATISTICS, SUB_TYPE, SUSPEND, TRANSACTION языку SQL READ RESERV RESERVING RESTRICT RETAIN ROLE SCHEMA SEGMENT SHADOW SHARED SINGULAR SIZE SNAPSHOT SORT STABILITY STARTING STARTS STATEMENT STATISTICS SUB_TYPE SUSPEND TRANSACTION TYPE UNCOMMITTED . ROLLBACK Доступно: DSQL, ESQL Синтаксис: ROLLBACK [WORK] [TRANSACTION tr_name] [RETAIN [SNAPSHOT] | TO [SAVEPOINT] sp_name | RELEASE] • Предложение TRANSACTION доступно только в ESQL; • Предложение

USHORT hdr_end; ULONG hdr_page_buffers; SLONG hdr_bumped_transaction; SLONG hdr_oldest_snapshot; SLONG hdr_backup_pages; SLONG hdr_misc[3]; UCHAR hdr_data[1]; }; hdr_header The database database have this field set to zero. hdr_oldest_snapshot Four bytes, signed. Bytes 0x4c - 0x4f on the page. Holds the transaction number for the oldest snapshot of active transactions. This is also documented hdr_bumped_transaction 0000004c 02 00 00 00 hdr_oldest_snapshot 00000050 00 00 00 00 hdr_backup_pages 00000054 00 00 00

In isql, a transaction is begun as soon as the utility is started. The transaction is begun in SNAPSHOT isolation, with a lock resolution set to WAIT. Since the Firebird isql utility accepts DDL, DML include: • NO AUTO UNDONE • IGNORE LIMBO • LOCK TIMEOUT number Example: SET TRANSACTION WAIT SNAPSHOT NO AUTO UNDONE LOCK TIMEOUT 10;  If you request help on the set in isql then the set transaction execution of the statement will appear to hang until the other session either commits or rolls back. • SNAPSHOT — meaning that this transaction will be guaranteed a non-volatile view of the data and will be

collected. Neither will affect the database’s OIT (Oldest Intersting Transaction) or OST (Oldest Snapshot) settings however. In practice, better do not consider backup as an alternative for sweep, because interval for a new database is 20,000. The sweep interval is the difference between the Oldest Snapshot Transaction, or OST and the Oldest Interesting Transaction or OIT.  This doesn’t mean that every gstat utility to check the database header page and extract the Oldest Transaction (OIT) and Oldest Snapshot (OST) numbers from the output. If OST - OIT is small (less than the sweep interval) then a manual

Хотя и возможно установить Firebird методом копирования, «раз-tar-ив» файл моментальной сборки (snapshot build) или разархивировав .zip файл, настоятельно рекомендуется, по крайней мере, для Ва- шего первого одновременно с обычной работой пользователей. Резерв будет осуществляться с моментальной копии (snapshot) состояния базы данных на время старта процедуры резервирования. Регулярное резервирование и случающееся

Although it is possible to install Firebird by a filesystem copying method – such as “untarring” a snapshot build file or decompressing a structured WinZip .zip file – it is strongly recommended that you users are connected to the system and going about their normal work. The backup will be taken from a snapshot of the database state at the time the backup began. Regular backups and occasional restores using