Oracle dataguard - Redo apply
In a low bandwidth environment when a transaction commits that generates a large amount of redo data will cause other independent transactions to slow down. This is because the redo data of small transactions will be blocked until the large redo data of the previous transaction is transported to the DR site. Is there a way that we can control small redo data takes priority over the large one so the other independent transactions complete quicker.
Any suggestions?
oracle-11g transaction rdbms dataguard
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
bumped to the homepage by Community♦ 21 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
add a comment |
In a low bandwidth environment when a transaction commits that generates a large amount of redo data will cause other independent transactions to slow down. This is because the redo data of small transactions will be blocked until the large redo data of the previous transaction is transported to the DR site. Is there a way that we can control small redo data takes priority over the large one so the other independent transactions complete quicker.
Any suggestions?
oracle-11g transaction rdbms dataguard
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
bumped to the homepage by Community♦ 21 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
If that was possible, you risk "starving" the large transactions, which isn't desired. If you really need SYNC dataguard, you should seriously consider getting a better network link.
– Mat
Sep 29 '14 at 15:15
add a comment |
In a low bandwidth environment when a transaction commits that generates a large amount of redo data will cause other independent transactions to slow down. This is because the redo data of small transactions will be blocked until the large redo data of the previous transaction is transported to the DR site. Is there a way that we can control small redo data takes priority over the large one so the other independent transactions complete quicker.
Any suggestions?
oracle-11g transaction rdbms dataguard
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
In a low bandwidth environment when a transaction commits that generates a large amount of redo data will cause other independent transactions to slow down. This is because the redo data of small transactions will be blocked until the large redo data of the previous transaction is transported to the DR site. Is there a way that we can control small redo data takes priority over the large one so the other independent transactions complete quicker.
Any suggestions?
oracle-11g transaction rdbms dataguard
oracle-11g transaction rdbms dataguard
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
asked Sep 29 '14 at 11:39
SashikaXPSashikaXP
1011
1011
bumped to the homepage by Community♦ 21 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
bumped to the homepage by Community♦ 21 mins ago
This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.
If that was possible, you risk "starving" the large transactions, which isn't desired. If you really need SYNC dataguard, you should seriously consider getting a better network link.
– Mat
Sep 29 '14 at 15:15
add a comment |
If that was possible, you risk "starving" the large transactions, which isn't desired. If you really need SYNC dataguard, you should seriously consider getting a better network link.
– Mat
Sep 29 '14 at 15:15
If that was possible, you risk "starving" the large transactions, which isn't desired. If you really need SYNC dataguard, you should seriously consider getting a better network link.
– Mat
Sep 29 '14 at 15:15
If that was possible, you risk "starving" the large transactions, which isn't desired. If you really need SYNC dataguard, you should seriously consider getting a better network link.
– Mat
Sep 29 '14 at 15:15
add a comment |
1 Answer
1
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No. The operations go to DR site in exactly the same sequential order as they were performed on the primary site. You can only re-order operations at the level of your application code, the database engine cannot do this for you.
The database engine cannot reorder changes to data because it needs to ensure that DR database is bit-to-bit identical to the state of primary database at a very recent point-in-time.
Your impression that COMMIT transfers all the data is incorrect. Data is transferred all the time throughout the transaction, and COMMIT is quite a small transfer itself that ends it. The only special thing about the COMMIT is that it is the only transfer for which the primary database has to wait until the COMMIT mark is transferred to DR, written there to disk, and acknowledged back to primary.
Anyway, I would strongly suggest to change SYNC to ASYNC in your archive_log_dest_x, which would obviously solve your problem (problem of waiting for COMMIT), at a cost of potential loss of the unsynchronized data in a real DR situation. If your software controls real-time multimillion FOREX transactions, and you have a high-bandwidth high-available network connection, then SYNC is the way to go. If not, you should accept this small risk, as most other users do.
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
add a comment |
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No. The operations go to DR site in exactly the same sequential order as they were performed on the primary site. You can only re-order operations at the level of your application code, the database engine cannot do this for you.
The database engine cannot reorder changes to data because it needs to ensure that DR database is bit-to-bit identical to the state of primary database at a very recent point-in-time.
Your impression that COMMIT transfers all the data is incorrect. Data is transferred all the time throughout the transaction, and COMMIT is quite a small transfer itself that ends it. The only special thing about the COMMIT is that it is the only transfer for which the primary database has to wait until the COMMIT mark is transferred to DR, written there to disk, and acknowledged back to primary.
Anyway, I would strongly suggest to change SYNC to ASYNC in your archive_log_dest_x, which would obviously solve your problem (problem of waiting for COMMIT), at a cost of potential loss of the unsynchronized data in a real DR situation. If your software controls real-time multimillion FOREX transactions, and you have a high-bandwidth high-available network connection, then SYNC is the way to go. If not, you should accept this small risk, as most other users do.
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
add a comment |
No. The operations go to DR site in exactly the same sequential order as they were performed on the primary site. You can only re-order operations at the level of your application code, the database engine cannot do this for you.
The database engine cannot reorder changes to data because it needs to ensure that DR database is bit-to-bit identical to the state of primary database at a very recent point-in-time.
Your impression that COMMIT transfers all the data is incorrect. Data is transferred all the time throughout the transaction, and COMMIT is quite a small transfer itself that ends it. The only special thing about the COMMIT is that it is the only transfer for which the primary database has to wait until the COMMIT mark is transferred to DR, written there to disk, and acknowledged back to primary.
Anyway, I would strongly suggest to change SYNC to ASYNC in your archive_log_dest_x, which would obviously solve your problem (problem of waiting for COMMIT), at a cost of potential loss of the unsynchronized data in a real DR situation. If your software controls real-time multimillion FOREX transactions, and you have a high-bandwidth high-available network connection, then SYNC is the way to go. If not, you should accept this small risk, as most other users do.
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
add a comment |
No. The operations go to DR site in exactly the same sequential order as they were performed on the primary site. You can only re-order operations at the level of your application code, the database engine cannot do this for you.
The database engine cannot reorder changes to data because it needs to ensure that DR database is bit-to-bit identical to the state of primary database at a very recent point-in-time.
Your impression that COMMIT transfers all the data is incorrect. Data is transferred all the time throughout the transaction, and COMMIT is quite a small transfer itself that ends it. The only special thing about the COMMIT is that it is the only transfer for which the primary database has to wait until the COMMIT mark is transferred to DR, written there to disk, and acknowledged back to primary.
Anyway, I would strongly suggest to change SYNC to ASYNC in your archive_log_dest_x, which would obviously solve your problem (problem of waiting for COMMIT), at a cost of potential loss of the unsynchronized data in a real DR situation. If your software controls real-time multimillion FOREX transactions, and you have a high-bandwidth high-available network connection, then SYNC is the way to go. If not, you should accept this small risk, as most other users do.
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
No. The operations go to DR site in exactly the same sequential order as they were performed on the primary site. You can only re-order operations at the level of your application code, the database engine cannot do this for you.
The database engine cannot reorder changes to data because it needs to ensure that DR database is bit-to-bit identical to the state of primary database at a very recent point-in-time.
Your impression that COMMIT transfers all the data is incorrect. Data is transferred all the time throughout the transaction, and COMMIT is quite a small transfer itself that ends it. The only special thing about the COMMIT is that it is the only transfer for which the primary database has to wait until the COMMIT mark is transferred to DR, written there to disk, and acknowledged back to primary.
Anyway, I would strongly suggest to change SYNC to ASYNC in your archive_log_dest_x, which would obviously solve your problem (problem of waiting for COMMIT), at a cost of potential loss of the unsynchronized data in a real DR situation. If your software controls real-time multimillion FOREX transactions, and you have a high-bandwidth high-available network connection, then SYNC is the way to go. If not, you should accept this small risk, as most other users do.
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
answered Oct 7 '14 at 18:09
kubanczykkubanczyk
1,642712
1,642712
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
add a comment |
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
Hmmm...this is one very good answer. A bit of background reading also confirmed this is how it happens. In fact during a large transaction the redo log buffer at SGA frequently writes redo records to the current active local redo log file as well as to the standby redo log file. So this means whats written to the local redo log is sync with the standby redo log. I was under the impression that the standby is synched through only by shipping a redo "log file" to the standby. But then the question comes how the redo wastage happens as there cant be any half filled redo log files.
– SashikaXP
Oct 8 '14 at 1:51
add a comment |
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If that was possible, you risk "starving" the large transactions, which isn't desired. If you really need SYNC dataguard, you should seriously consider getting a better network link.
– Mat
Sep 29 '14 at 15:15