GS_TXN_LSN_TIME

GS_TXN_LSN_TIME records the mapping between logical decoding commit sequence numbers, log sequence numbers, and timestamps. In a distributed environment, it contains data only on DNs.

**Table 1** GS_TXN_LSN_TIME columns
Column	Type	Description
create_csn	bigint	Commit sequence number.
create_lsn	bigint	Log sequence number.
snp_xmin	bigint	Minimum snapshot ID.
snp_snapshot	text	Serialized snapshot text.
barrier	text	Barrier information.
create_time	timestamp with time zone	Timestamp when a tuple is inserted.

create_lsn is stored as a number in the system catalog. An LSN can be converted to the common LSN format (for reference only), that is, XXXXXXXX/XXXXXXXX, using the SQL syntax. The conversion syntax is as follows:
```
SELECT CONCAT(to_hex(({lsn_num}::bigint >> 32) & x'ffffffff'::bigint), '/', to_hex(({lsn_num}::bigint << 32 >> 32) & x'ffffffff'::bigint));
```
When using the preceding SQL statement, convert lsn_num to the required number. The following uses 607906688 as an example:
```
gaussdb=# SELECT CONCAT(to_hex((607906688::bigint >> 32) & x'ffffffff'::bigint), '/', to_hex((607906688::bigint << 32 >> 32) & x'ffffffff'::bigint));
concat
------------
0/243beb80
(1 row)
```
The M-compatible syntax is different from the GaussDB syntax. Therefore, in an M-compatible database, you need to perform the following conversion:
```
SELECT CONCAT(hex(({lsn_num} >> 32) & 4294967295), '/', hex((({lsn_num}<< 32) >> 32) & 4294967295));
```
When using the preceding SQL statement, convert lsn_num to the required number. The following uses 607906688 as an example:
```
gaussdb_m=# SELECT CONCAT(hex((607906688 >> 32) & 4294967295), '/', hex(((607906688 << 32) >> 32) & 4294967295));
   concat
------------
 0/243BEB80
(1 row)
```