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From "Shreepadma Venugopalan" <>
Subject Re: Review Request: HIVE-1362: Support for column statistics in Hive
Date Wed, 03 Oct 2012 03:10:51 GMT

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(Updated Oct. 3, 2012, 3:10 a.m.)

Review request for hive and Carl Steinbach.


This patch addresses the comments from revision # 1 and makes the following changes,

* Splits the ColumnStatistics thrift structure in such a way that the thrift API is locked
* Splits the writeColumnStatistics API to updateTable.. and updatePartition... to separate
out partition and table level updates
* Adds comments to the Thrift RPC calls
* Logs the record that is being written in update[Table/Partition]ColumnStatistics to identify
the bad record in case of a failed update
* Uses a consistent naming convention for the Thrift APIs
* Incorporates the rest of the misc. review comments from revision # 1.


This patch implements version 1 of the column statistics project in Hive. It adds support
for computing and persisting statistical summary of column values in Hive Tables and Partitions.
In order to support column statistics in Hive, this patch does the following,

* Adds a new compute stats UDAF to compute scalar statistics for all primitive Hive data types.
In version 1 of the project, we support the following scalar statistics on primitive types
- estimate of number of distinct values, number of null values, number of trues/falses for
boolean typed columsn, max and avg length for string and binary typed columns, max and min
value for long and double typed columns. Note that version 1 of the column stats project includes
support for column statistics both at the table and partition level.

* Adds Metastore schema tables to persist the newly added statistics both at table and partition
* Adds Metastore Thrift API to persist, retrieve and delete column statistics at both table
and partition level. 
Please refer to the following wiki link for the details of the schema and the Thrift API changes

* Extends the analyze table compute statistics statement to trigger statistics computation
and persistence for one or more columns. Please note that statistics for multiple columns
is computed through a single scan of the table data. Please refer to the following wiki link
for the syntax changes -

One thing missing from the patch at this point is the metastore upgrade scrips for MySQL/Derby/Postgres/Oracle.
I'm waiting for the review to finalize the metastore schema changes before I go ahead and
add the upgrade scripts.

In a follow on patch, as part of version 2 of the column statistics project, we will add support
for computing, persisting and retrieving histograms on long and double typed column values.

Generated Thrift files have been removed for viewing pleasure. JIRA page has the patch with
the generated Thrift files.

This addresses bug HIVE-1362.

Diffs (updated)

  data/files/UserVisits.dat PRE-CREATION 
  data/files/binary.txt PRE-CREATION 
  data/files/bool.txt PRE-CREATION 
  data/files/double.txt PRE-CREATION 
  data/files/employee.dat PRE-CREATION 
  data/files/employee2.dat PRE-CREATION 
  data/files/int.txt PRE-CREATION 
  ivy/ 7ac6778 
  metastore/if/hive_metastore.thrift d4fad72 
  metastore/src/java/org/apache/hadoop/hive/metastore/ 8fec13d 
  metastore/src/java/org/apache/hadoop/hive/metastore/ 17b986c 
  metastore/src/java/org/apache/hadoop/hive/metastore/ 3883b5b 
  metastore/src/java/org/apache/hadoop/hive/metastore/ eff44b1 
  metastore/src/java/org/apache/hadoop/hive/metastore/ bf5ae3a 
  metastore/src/java/org/apache/hadoop/hive/metastore/ 77d1caa 
  metastore/src/model/org/apache/hadoop/hive/metastore/model/ PRE-CREATION

  metastore/src/model/package.jdo 38ce6d5 
  metastore/src/test/org/apache/hadoop/hive/metastore/ 528a100

  metastore/src/test/org/apache/hadoop/hive/metastore/ 925938d 
  ql/build.xml 5de3f78 
  ql/if/queryplan.thrift 05fbf58 
  ql/ivy.xml aa3b8ce 
  ql/src/java/org/apache/hadoop/hive/ql/exec/ PRE-CREATION 
  ql/src/java/org/apache/hadoop/hive/ql/exec/ 425900d 
  ql/src/java/org/apache/hadoop/hive/ql/exec/ 4c8831f 
  ql/src/java/org/apache/hadoop/hive/ql/exec/ 4446952 
  ql/src/java/org/apache/hadoop/hive/ql/exec/ 79b87f1 
  ql/src/java/org/apache/hadoop/hive/ql/metadata/ 7440889 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ 344dc69 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ f7257cd 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ e75a075 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ 61bc7fd 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ 6024dd4 
  ql/src/java/org/apache/hadoop/hive/ql/parse/Hive.g 356779a 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ 09ef969 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ 22fa20f 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ a0ccbe6 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ b38c002 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ 5ce31f1 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ ad1a14c 
  ql/src/java/org/apache/hadoop/hive/ql/parse/ PRE-CREATION 
  ql/src/java/org/apache/hadoop/hive/ql/plan/ PRE-CREATION 
  ql/src/java/org/apache/hadoop/hive/ql/plan/ PRE-CREATION 
  ql/src/java/org/apache/hadoop/hive/ql/plan/ cb54753 
  ql/src/java/org/apache/hadoop/hive/ql/udf/generic/ PRE-CREATION

  ql/src/java/org/apache/hadoop/hive/ql/udf/generic/ PRE-CREATION

  ql/src/java/org/apache/hadoop/hive/ql/udf/generic/ PRE-CREATION

  ql/src/java/org/apache/hadoop/hive/ql/udf/generic/ PRE-CREATION

  ql/src/java/org/apache/hadoop/hive/ql/udf/generic/ PRE-CREATION

  ql/src/test/queries/clientpositive/columnstats_partlvl.q PRE-CREATION 
  ql/src/test/queries/clientpositive/columnstats_tbllvl.q PRE-CREATION 
  ql/src/test/queries/clientpositive/compute_stats_binary.q PRE-CREATION 
  ql/src/test/queries/clientpositive/compute_stats_boolean.q PRE-CREATION 
  ql/src/test/queries/clientpositive/compute_stats_double.q PRE-CREATION 
  ql/src/test/queries/clientpositive/compute_stats_long.q PRE-CREATION 
  ql/src/test/queries/clientpositive/compute_stats_string.q PRE-CREATION 
  ql/src/test/results/clientpositive/columnstats_partlvl.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/columnstats_tbllvl.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/compute_stats_binary.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/compute_stats_boolean.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/compute_stats_double.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/compute_stats_long.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/compute_stats_string.q.out PRE-CREATION 
  ql/src/test/results/clientpositive/show_functions.q.out 02f6a94 
  ql/src/test/results/clientpositive/udaf_histogram.q.out PRE-CREATION 



All the existing hive tests pass. Additionally this patch adds the following unit tests,

* Tests to to test the Metastore schema and Thrift API changes,
* Tests to exercise compute_stats UDAF for all primitive types,
* End to end test both at table and partition level for computing stats on multiple columns.
Note that these tests use the extended syntax of the analyze command.


Shreepadma Venugopalan

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