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firebird-mirror/doc/sql.extensions/README.isc_info_xxx
asfernandes f0de59cde9 Misc
2009-02-13 21:08:56 +00:00

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New information items
Author:
Vlad Khorsun <hvlad at users.sourceforge.net>
New items for isc_database_info
1. isc_info_active_tran_count :
return number of currently active transactions
2. isc_info_creation_date :
return date and time when database was created
To decode call isc_vax_integer twice to extract (first) date
and (second) time portions of ISC_TIMESTAMP. Then use
isc_decode_timestamp as usual
3. fb_info_page_contents :
return contents of some database page
Query format is <fb_info_page_contents> <length> <page_number>, where
<length> is 2-byte length of <page_number>
<page_number> is 4-byte number of requested page.
In the future it will be possible to pass 8-byte page_number value
including both page number and page space number.
Response format is <fb_info_page_contents, length, page_content>, where
<length> is 2-byte length of <page_content> and is equal to database
page size
This feature is allowed only for SYSDBA or database owner for security
reasons. Introduced in Firebird v2.5.
See also CORE-2054.
New items for isc_transaction_info:
1. isc_info_tra_oldest_interesting :
return number of oldest interesting transaction when current
transaction started. For snapshot transactions this is also the
number of oldest transaction in the private TIP copy
2. isc_info_tra_oldest_active
for read-committed transaction return number of current transaction
for other transactions return number of oldest active transaction
when current transaction started
3. isc_info_tra_oldest_snapshot
return minimum number of tra_oldest_active of all active transactions
when current transaction started.
This value is used as garbage collection threshold
4. isc_info_tra_isolation
return transaction isolation mode of current transaction.
format of returned clumplets is following:
isc_info_tra_isolation,
1, isc_info_tra_consistency | isc_info_tra_concurrency
|
2, isc_info_tra_read_committed,
isc_info_tra_no_rec_version | isc_info_tra_rec_version
i.e. for read committed transactions returned 2 items while for
other transactions returned 1 item
5. isc_info_tra_access
return read-write access mode of current transaction.
format of returned clumplets is following:
isc_info_tra_access, 1, isc_info_tra_readonly | isc_info_tra_readwrite
6. isc_info_tra_lock_timeout
return lock timeout of current transaction