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Posted to commits@carbondata.apache.org by ja...@apache.org on 2017/06/20 07:29:16 UTC
[10/56] [abbrv] carbondata git commit: Create
useful-tips-on-carbondata.md
Create useful-tips-on-carbondata.md
Project: http://git-wip-us.apache.org/repos/asf/carbondata/repo
Commit: http://git-wip-us.apache.org/repos/asf/carbondata/commit/425e9f55
Tree: http://git-wip-us.apache.org/repos/asf/carbondata/tree/425e9f55
Diff: http://git-wip-us.apache.org/repos/asf/carbondata/diff/425e9f55
Branch: refs/heads/streaming_ingest
Commit: 425e9f55a4852d969dc9f934eb4f21710cad08a5
Parents: eb9dbfa
Author: chenerlu <ch...@huawei.com>
Authored: Tue Jun 13 15:05:16 2017 +0800
Committer: chenliang613 <ch...@apache.org>
Committed: Wed Jun 14 09:54:46 2017 +0800
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docs/useful-tips-on-carbondata.md | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
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http://git-wip-us.apache.org/repos/asf/carbondata/blob/425e9f55/docs/useful-tips-on-carbondata.md
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diff --git a/docs/useful-tips-on-carbondata.md b/docs/useful-tips-on-carbondata.md
index 9bc5a46..9f290c7 100644
--- a/docs/useful-tips-on-carbondata.md
+++ b/docs/useful-tips-on-carbondata.md
@@ -98,7 +98,7 @@ The create table command can be modified as below :
```
create table carbondata_table(
Dime_1 String,
- BEGIN_TIME bigint
+ BEGIN_TIME bigint,
HOST String,
MSISDN String,
...
@@ -116,7 +116,7 @@ query performance. The create table command can be modified as below :
```
create table carbondata_table(
Dime_1 String,
- BEGIN_TIME bigint
+ BEGIN_TIME bigint,
HOST String,
MSISDN String,
counter_1 double,
@@ -132,8 +132,8 @@ query performance. The create table command can be modified as below :
* **Columns of incremental character should be re-arranged at the end of dimensions**
- Consider the following scenario where data is loaded each day and the start_time is incremental for each load, it is
-suggested to put start_time at the end of dimensions.
+ Consider the following scenario where data is loaded each day and the begin_time is incremental for each load, it is
+suggested to put begin_time at the end of dimensions.
Incremental values are efficient in using min/max index. The create table command can be modified as below :
@@ -170,12 +170,12 @@ excessive memory usage.
CarbonData supports large data load, in this process sorting data while loading consumes a lot of memory and disk IO and
this can result sometimes in "Out Of Memory" exception.
If you do not have much memory to use, then you may prefer to slow the speed of data loading instead of data load failure.
- You can configure CarbonData by tuning following properties in carbon.properties file to get a better performance.:
+ You can configure CarbonData by tuning following properties in carbon.properties file to get a better performance.
| Parameter | Default Value | Description/Tuning |
|-----------|-------------|--------|
|carbon.number.of.cores.while.loading|Default: 2.This value should be >= 2|Specifies the number of cores used for data processing during data loading in CarbonData. |
-|carbon.sort.size|Default: 100000. The value should be >= 100.|Threshhold to write local file in sort step when loading data|
+|carbon.sort.size|Default: 100000. The value should be >= 100.|Threshold to write local file in sort step when loading data|
|carbon.sort.file.write.buffer.size|Default: 50000.|DataOutputStream buffer. |
|carbon.number.of.cores.block.sort|Default: 7 | If you have huge memory and cpus, increase it as you will|
|carbon.merge.sort.reader.thread|Default: 3 |Specifies the number of cores used for temp file merging during data loading in CarbonData.|
@@ -183,7 +183,7 @@ excessive memory usage.
For example, if there are 10 million records ,and i have only 16 cores ,64GB memory, will be loaded to CarbonData table.
-Using the default configuration always fail in sort step. Modify carbon.properties as suggested below
+Using the default configuration always fail in sort step. Modify carbon.properties as suggested below:
```
@@ -204,8 +204,8 @@ scenarios. After the completion of POC, some of the configurations impacting the
| carbon.sort.intermediate.files.limit | spark/carbonlib/carbon.properties | Data loading | During the loading of data, local temp is used to sort the data. This number specifies the minimum number of intermediate files after which the merge sort has to be initiated. | Increasing the parameter to a higher value will improve the load performance. For example, when we increase the value from 20 to 100, it increases the data load performance from 35MB/S to more than 50MB/S. Higher values of this parameter consumes more memory during the load. |
| carbon.number.of.cores.while.loading | spark/carbonlib/carbon.properties | Data loading | Specifies the number of cores used for data processing during data loading in CarbonData. | If you have more number of CPUs, then you can increase the number of CPUs, which will increase the performance. For example if we increase the value from 2 to 4 then the CSV reading performance can increase about 1 times |
| carbon.compaction.level.threshold | spark/carbonlib/carbon.properties | Data loading and Querying | For minor compaction, specifies the number of segments to be merged in stage 1 and number of compacted segments to be merged in stage 2. | Each CarbonData load will create one segment, if every load is small in size it will generate many small file over a period of time impacting the query performance. Configuring this parameter will merge the small segment to one big segment which will sort the data and improve the performance. For Example in one telecommunication scenario, the performance improves about 2 times after minor compaction. |
-| spark.sql.shuffle.partitions | spark/con/spark-defaults.conf | Querying | The number of task started when spark shuffle. | The value can be 1 to 2 times as much as the executor cores. In an aggregation scenario, reducing the number from 200 to 32 reduced the query time from 17 to 9 seconds. |
-| num-executors/executor-cores/executor-memory | spark/con/spark-defaults.conf | Querying | The number of executors, CPU cores, and memory used for CarbonData query. | In the bank scenario, we provide the 4 CPUs cores and 15 GB for each executor which can get good performance. This 2 value does not mean more the better. It needs to be configured properly in case of limited resources. For example, In the bank scenario, it has enough CPU 32 cores each node but less memory 64 GB each node. So we cannot give more CPU but less memory. For example, when 4 cores and 12GB for each executor. It sometimes happens GC during the query which impact the query performance very much from the 3 second to more than 15 seconds. In this scenario need to increase the memory or decrease the CPU cores. |
+| spark.sql.shuffle.partitions | spark/conf/spark-defaults.conf | Querying | The number of task started when spark shuffle. | The value can be 1 to 2 times as much as the executor cores. In an aggregation scenario, reducing the number from 200 to 32 reduced the query time from 17 to 9 seconds. |
+| spark.executor.instances/spark.executor.cores/spark.executor.memory | spark/conf/spark-defaults.conf | Querying | The number of executors, CPU cores, and memory used for CarbonData query. | In the bank scenario, we provide the 4 CPUs cores and 15 GB for each executor which can get good performance. This 2 value does not mean more the better. It needs to be configured properly in case of limited resources. For example, In the bank scenario, it has enough CPU 32 cores each node but less memory 64 GB each node. So we cannot give more CPU but less memory. For example, when 4 cores and 12GB for each executor. It sometimes happens GC during the query which impact the query performance very much from the 3 second to more than 15 seconds. In this scenario need to increase the memory or decrease the CPU cores. |
| carbon.detail.batch.size | spark/carbonlib/carbon.properties | Data loading | The buffer size to store records, returned from the block scan. | In limit scenario this parameter is very important. For example your query limit is 1000. But if we set this value to 3000 that means we get 3000 records from scan but spark will only take 1000 rows. So the 2000 remaining are useless. In one Finance test case after we set it to 100, in the limit 1000 scenario the performance increase about 2 times in comparison to if we set this value to 12000. |
| carbon.use.local.dir | spark/carbonlib/carbon.properties | Data loading | Whether use YARN local directories for multi-table load disk load balance | If this is set it to true CarbonData will use YARN local directories for multi-table load disk load balance, that will improve the data load performance. |