[jira] [Commented] (HBASE-5504) Online Merge
[
https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13564618#comment-13564618
]
Jean-Marc Spaggiari commented on HBASE-5504:
Seems there is no activities on this JIRA for almost a year now, and 7403 seems
to be close to be released.
Should we close thise one?
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: Client, master, shell, Zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
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https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13257523#comment-13257523
]
Eric Newton commented on HBASE-5504:
We implemented delayed file cleanup because that is what was described in the
BigTable paper. A tablet will have files in multiple directories, including
directories under different tables, as is the case just after a table copy.
The file information is stored in the metadata table. Splits, bulk import and
table copying all create references to files, which remain shared. Data will
exist in the file, but outside the tablet's range, which is why we chop them
during merge. The tablet server keeps the list up-to-date in the metadata
table as files are bulk loaded and compacted. We also keep the list of files
that are candidates for deletion in the metadata table, so we aren't asking the
NameNode for information about files during GC. Bulk import, compaction, and
gc must all be coordinated such that the file isn't inadvertently deleted while
still being imported into other tablets.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
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https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13247307#comment-13247307
]
stack commented on HBASE-5504:
--
Hey Eric. Thanks for the help. Looking at FATE it didn't look like we could
pull it over easily (maybe I should look again) but for sure we need to emulate
something like it. First up would be table read/write lock and have actions
like split (or bulk import) take out at a read lock before progressing. Can I
have a pointer for your file GCer, on why delayed cleanup? So you'd keep up in
meta the list of files for a range and this would be the region/tablets' list
even though the files might not sit physically under a particular region/tablet
(What about compactions? Would it have to update the list in the meta table
when it moved the compacted file into place?). On point 1., isn't it possible
a file might still over-span a range?
Good stuff.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
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https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13246885#comment-13246885
]
Eric Newton commented on HBASE-5504:
Hi,
I work on Accumulo, and I implemented the merge/deleteRange feature.
Our primary use-case was a time-based row, in which data was being deleted as
it aged. Over time, this created splits that were empty and resulted in poor
balancing. The same goes for deleteRange. It is now very efficient to tell
Accumulo: delete all rows that fall before 20111231.
I know that stack and Keith Turner have commented on other tickets and
referenced the FATE architecture. It really simplified the many steps in merge
(see the outline in this ticket). FATE is not very big and would be easy to
borrow/emulate.
We also added the concept of read and write locks on tables. Merge grabs a
write lock on a table, and so does bulk import. This reduces the number of
assumptions each of the processes has to understand.
Accumulo has a file garbage collector, so files can survive many splits. But
this makes merge more complex because files containing data for an unused
section of a file in a split might be re-used in a merge, and that data might
have been deleted. A merge would inadvertently bring that data back. We had at
least two implementation options:
1. keep range information with files in the metadata tablet
2. chop files, or compact a file down to the tablet's range before the merge
We chose option 2. This might appeal to the HBase community, too, since it
avoids double-indirection and file-deletion issues. But I regret not using
option 1 because it would have made merge as fast as split.
Our merge works on a range. But we have tools that allow a user to merge based
on their tablet size. But this only works with one range at a time. It also
requires the tablet to go online to perform the chop operation. If a user
decides to change their tablet size from 256M to 1G, and their table size is
1P, they will wait a very long time. In the future we will recognize this case
and chop the tablets in parallel and take the table offline to re-write the
metadata table.
I know we found a lot of places in Accumulo where we assumed that tablets would
only split. It took a lot of testing to discover these assumptions.
Fortunately merge/split are isomorphic and can be used to test the each other.
DeleteRange, while very similar to merge, does not have this property and is
harder to test at scale.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M -
[jira] [Commented] (HBASE-5504) Online Merge
[
https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13221023#comment-13221023
]
stack commented on HBASE-5504:
--
bq. I meant that data for the neighbor region we choose should be copied. The
neighbor region would have new delimiting key.
Sorry, I'm not following Ted. You need to bring me a long. Thanks.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
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https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13221179#comment-13221179
]
stack commented on HBASE-5504:
--
@Ted that takes me to a comment I made. I still am without understanding.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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]
Zhihong Yu commented on HBASE-5504:
---
Since region splitting is disabled after step 3, how do we deal with the case
where the start of row range lies in the middle of a region ?
For step 6:
bq. if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table
I like the above approach. We can create a sub-task which is to be done after
HBASE-5494 goes in.
For step 14, we still need to move data for delete region request because we
should have chosen one of the neighbor regions to cover the hole in .META.
What if the master crashes anywhere between step 6 and step 19 ? How would the
new master deal with the outstanding table lock ?
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Labels: noob
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
[
https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13220572#comment-13220572
]
Mubarak Seyed commented on HBASE-5504:
--
bq. What if the master crashes anywhere between step 6 and step 19 ? How would
the new master deal with the outstanding table lock ?
I think new active master (after failover) should resume executing task
(provided state is maintained in table lock znode)
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Labels: noob
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
[
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]
Mubarak Seyed commented on HBASE-5504:
--
How do we get around if merge/delete-range get stuck (it should not but if it
happens???), can we provide a tool to fail or delete? (something like admin
operation). User can delete the lock znode in ZK (thats the worst case)? Can we
make use of [HBASE-5459|https://issues.apache.org/jira/browse/HBASE-5459]?
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Labels: noob
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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]
Zhihong Yu commented on HBASE-5504:
---
w.r.t. the comment @ 02/Mar/12 01:18,
Is it possible that there would be more than one master-coordinated task for
the same table running at the same time ?
If so, what should the state store ?
I think we should remove the noob label for this JIRA.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Labels: noob
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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]
Mubarak Seyed commented on HBASE-5504:
--
bq. Is it possible that there would be more than one master-coordinated task
for the same table running at the same time ?
If we store like /hbase/lock/table_name then we can't. How about
{code}
/hbase/lock/table_name/lockNode1
/lockNode1
{code}
lockNode1 for task1 and be W, lockNode2 for task2 and be R
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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]
Mubarak Seyed commented on HBASE-5504:
--
[HBASE-5494|https://issues.apache.org/jira/browse/HBASE-5494] says only one
table operation at a time.
@Stack
What happens if task (which held the lock) get stuck?
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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]
Mubarak Seyed commented on HBASE-5504:
--
bq. Since region splitting is disabled after step 3, how do we deal with the
case where the start of row range lies in the middle of a region ?
I think we were discussing about start/end key should match with region
boundary (single or multiple), isn't? Are we planning to do arbitrary start/end
key?
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
[
https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13220669#comment-13220669
]
Zhihong Yu commented on HBASE-5504:
---
So there is validation at step 2 for region boundary check. That's fine.
In first version, we can disable region splitting.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
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]
stack commented on HBASE-5504:
--
bq. Since region splitting is disabled after step 3, how do we deal with the
case where the start of row range lies in the middle of a region ?
Good question. How about, if a merge, we include the hosting region in the
merge. If a delete region, we throw an exception saying you need to specify
region edges.
bq. For step 14, we still need to move data for delete region request because
we should have chosen one of the neighbor regions to cover the hole in .META.
I think this comes of a misunderstanding that you might have Ted. You can't
alter region edges once created. For example, the directory in hdfs is the
hash of regionname which includes at least the startkey and should one day
include the endkey... If you change the delimiting keys, you have to make a new
region. Were you thinking we could change the delimiting keys on an existing
region?
On 'What if the master crashes anywhere between step 6 and step 19 ?', its what
Mubarak says; the new master comes up and after initializing, tries to pick up
merge/delete from where the previous master left off... Or simpler, it could
just undo it all?
bq. How do we get around if merge/delete-range get stuck (it should not but if
it happens???)
I think we need to make the operation cancelable? In shell/api, there'd be a
cancel operation on table! (Since you need a write lock to do one of these
operations, this would mean one operation at a time per table only. maybe
no need of there being a lock transaction id because only one happening at a
time?)
Later we can do something better where if an operation does not complete, the
master operation runner would do the cancel.. but that we could do later?
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
[jira] [Commented] (HBASE-5504) Online Merge
[
https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13220734#comment-13220734
]
Lars Hofhansl commented on HBASE-5504:
--
.bq 18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
That's would be awesome for a variety of other reason. For example snapshots.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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[jira] [Commented] (HBASE-5504) Online Merge
[
https://issues.apache.org/jira/browse/HBASE-5504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13220743#comment-13220743
]
Zhihong Yu commented on HBASE-5504:
---
bq. You can't alter region edges once created.
Understood.
I meant that data for the neighbor region we choose should be copied. The
neighbor region would have new delimiting key.
Online Merge
Key: HBASE-5504
URL: https://issues.apache.org/jira/browse/HBASE-5504
Project: HBase
Issue Type: Brainstorming
Components: client, master, shell, zookeeper
Affects Versions: 0.94.0
Reporter: Mubarak Seyed
Fix For: 0.96.0
As discussed, please refer the discussion at
[HBASE-4991|https://issues.apache.org/jira/browse/HBASE-4991]
Design suggestion from Stack:
{quote}
I suggest a design below. It has some prerequisites, some general function
that this feature could use (and others). The prereqs if you think them good,
could be done outside of this JIRA.
Here's a suggested rough outline of how I think this feature should run. The
feature I'm describing below is merge and deleteRegion for I see them as in
essence the same thing.
(C) Client, (M) Master, RS (Region server), ZK (ZooKeeper)
1. Client calls merge or deleteRegion API. API is a range of rows. (C)
2. Master gets call. (M)
3. Master obtains a write lock on table so it can't be disabled from under
us. The write lock will also disable splitting. This is one of the prereqs I
think. Its HBASE-5494 (Or we could just do something simpler where we have a
flag up in zk that splitRegion checks but thats less useful I think; OR we do
the dynamic configs issue and set splits to off via a config. change).
There'd be a timer for how long we wait on the table lock. (M - ZK)
4. If we get the lock, write intent to merge a range up into zk. It also
hoists into zk if its a pure merge or a merge that drops the region data (a
deleteRegion call) (M)
5. Return to the client either our failed attempt at locking the table or an
id of some sort used identifying this running operation; can use it querying
status. (M - C)
6. Turn off balancer. TODO/prereq: Do it in a way that is persisted. Balancer
switch currently in memory only so if master crashes, new master will come up
in balancing mode # (If we had dynamic config. could hoist up to zk a config.
that disables the balancer rather than have a balancer-specific flag/znode OR
if a write lock outstanding on a table, then the balancer does not balance
regions in the locked table - this latter might be the easiest to do) (M)
7. Write into zk that just turned off the balancer (If it was on) (M - ZK)
8. Get regions that are involved in the span (M)
9. Hoist the list up into zk. (M - ZK)
10. Create region to span the range. (M)
11. Write that we did this up into zk. (M - ZK)
12. Close regions in parallel. Confirm close in parallel. (M - RS)
13. Write up into zk regions closed (This might not be necessary since can
ask if region is open). (M - ZK)
14. If a merge and not a delete region, move files under new region. Might
multithread this (moves should go pretty fast). If a deleteregion, we skip
this step. (M)
15. On completion mark zk (though may not be necessary since its easy to look
in fs to see state of move). (M - ZK)
16. Edit .META. (M)
17. Confirm edits went in. (M)
18. Move old regions to hbase trash folder TODO: There is no trash folder
under /hbase currently. We should add one. (M)
19. Enable balancer (if it was off) (M)
20. Unlock table (M)
{quote}
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