# How to delete empty partitions?

**URL:** <https://community.cratedb.com/t/how-to-delete-empty-partitions/480>\
**Category:** CrateDB\
**Created:** [August 26, 2020, 9:24am UTC](https://community.cratedb.com/t/how-to-delete-empty-partitions/480 "2020-08-26T09:24:41Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nrvmodi](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/nrvmodi/32/194_2.png) [@nrvmodi](https://community.cratedb.com/u/nrvmodi)\
**Post date:** [August 26, 2020, 9:24am UTC](https://community.cratedb.com/t/how-to-delete-empty-partitions/480/1 "2020-08-26T09:24:42Z")

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We have one table in which we are doing partition based on day.  
we will take snapshot of tables based on that partition and after taking backup we delete the data of that day.

Due to multiple partition, shards count is more than 2000 and configured shard is 6

I have observed that old partitions have no data but still exist in database.  
So it will take more time to become healthy and available to write data after restarting the crate.

 ![shard](https://us1.discourse-cdn.com/flex020/uploads/crate/original/1X/269a81a08db2f9d3fecfeca8909ab582ebca64cb.png)

So Is there any way to delete those partition?

Is there any way to stop replication of data on startup the cluster? cause it takes too much time to become healthy cluster and due to that table is not writable until that process finished.

Any solution for this issue will be great help?

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**Author:** ![smu](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/smu/32/60_2.png) [@smu](https://community.cratedb.com/u/smu)\
**Post date:** [August 27, 2020, 12:02pm UTC](https://community.cratedb.com/t/how-to-delete-empty-partitions/480/2 "2020-08-27T12:02:34Z")

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It would be very helpful to know the CrateDB version you are running and observing these issues.

> Is there any way to stop replication of data on startup the cluster? cause it takes too much time to become healthy cluster and due to that table is not writable until that process finished.

On CrateDB versions 2.0.0 up to 4.0.x, per default writing was only possible if all shards (primaries + replicas) were available. See [https://crate.io/docs/crate/reference/en/3.3/sql/statements/create-table.html#sql-ref-write-wait-for-active-shards](https://crate.io/docs/crate/reference/en/3.3/sql/statements/create-table.html#sql-ref-write-wait-for-active-shards).

We have changed the default back to `1` in CrateDB \>= 4.2. See

> **[Version 4.1.0](https://cratedb.com/docs/crate/reference/en/4.8/appendices/release-notes/4.1.0.html)**
>
> Released on 2020/01/15. Table of Contents Breaking Changes, Deprecations, Changes- Resiliency improvements, Performance improvements, SQL Standard and PostgreSQL compatibility improvements- Window function extensions, Functions and operators., New...

You can always change the default by:  
`ALTER TABLE my_table SET ("write.wait_for_active_shards" = 1);`

Additionally you can disable allocation of replica shards before shutting down the cluster:

`SET GLOBAL cluster.routing.allocation.enable = 'primaries';`

Of course this setting must be adjusted (reset) after the restart at some point, e.g.

`RESET GLOBAL cluster.routing.allocation.enable;`

See [Runtime configuration — CrateDB: Reference](https://crate.io/docs/crate/reference/en/4.2/admin/runtime-config.html#administration-runtime-config) for further readings on runtime settings.

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<div class="post-metadata">

**Author:** ![nrvmodi](https://sea2.discourse-cdn.com/flex020/user_avatar/community.cratedb.com/nrvmodi/32/194_2.png) [@nrvmodi](https://community.cratedb.com/u/nrvmodi)\
**Post date:** [August 31, 2020, 9:19am UTC](https://community.cratedb.com/t/how-to-delete-empty-partitions/480/3 "2020-08-31T09:19:29Z")

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Thanks for your reply.  
We are using 4.0.7 cratedb version

In my scenario, we are using **days** (current day midnight epoch) as a partition for table and we have configured 8 shards and table retention is 15-45 days for records.

So due to partition and retention, It will create around **1400-2500** shards for single table

**Can I choose days column for partition?**

**Does this multiple shards create bad impact on read/write performance?**

I have read [https://crate.io/docs/crate/howtos/en/latest/performance/sharding.html](https://crate.io/docs/crate/howtos/en/latest/performance/sharding.html)  
We have 2 core cpu, 8 gb ram around 3-4 nodes.  
As per guide, shard count should be equal to cpu count.

**Is it over allocation for table?**  
**What should I need to do to avoid this over allocation?**  
**What is the difference between Configured shards vs Started shards?**

  
  
Regarding the more partition, How can I delete partitions from the table? 

We have just find the workaround using close partition by below query.

Is there any performance impact if we close partition using below query?  
`ALTER TABLE my_table PARTITION (days=epoch) CLOSE;`