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Posted to issues@iceberg.apache.org by GitBox <gi...@apache.org> on 2020/09/17 03:01:03 UTC
[GitHub] [iceberg] JingsongLi commented on a change in pull request #1464: Flink: Add flink sink document
JingsongLi commented on a change in pull request #1464:
URL: https://github.com/apache/iceberg/pull/1464#discussion_r489913208
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File path: site/docs/flink.md
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+ - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ -->
+
+# Flink
+
+Apache Iceberg support both [Apache Flink](https://flink.apache.org/)'s DataStream API and Table API to write records into iceberg table. Currently,
+we only integrate iceberg with apache flink 1.11.x .
+
+| Feature support | Flink 1.11.0 | Notes |
+|------------------------------------------------------------------------|--------------------|--------------------------------------------------------|
+| [SQL create catalog](#creating-catalogs-and-using-catalogs) | ✔️ | |
+| [SQL create database](#create-database) | ✔️ | |
+| [SQL create table](#create-table) | ✔️ | |
+| [SQL alter table](#alter-table) | ✔️ | |
+| [SQL drop_table](#drop-table) | ✔️ | |
+| [SQL select](#querying-with-sql) | ️ | |
+| [SQL insert into](#insert-into) | ✔️ ️ | Support both streaming and batch mode |
+| [SQL insert overwrite](#insert-overwrite) | ✔️ ️ | |
+| [DataStream read](#reading-with-datastream) | ✔️ ️ | |
+| [DataStream append](#appending-data) | ✔️ ️ | |
+| [DataStream overwrite](#overwrite-data) | ✔️ ️ | |
+| [Metadata tables](#inspecting-tables) | ️ | |
+
+## Preparation
+
+To create iceberg table in flink, we recommend to use [Flink SQL Client](https://ci.apache.org/projects/flink/flink-docs-stable/dev/table/sqlClient.html) because it's easier
+for users to understand the concepts.
+
+Step.1 Downloading the flink 1.11.x binary package from the apache flink [download page](https://flink.apache.org/downloads.html).
+
+```bash
+wget https://downloads.apache.org/flink/flink-1.11.1/flink-1.11.1-bin-scala_2.11.tgz
+tar xzvf flink-1.11.1-bin-scala_2.11.tgz
+```
+
+Step.2 Start a standalone flink cluster within hadoop environment.
+
+```bash
+# HADOOP_HOME is your hadoop root directory after unpack the binary package.
+export HADOOP_CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath`
+
+# Start the flink standalone cluster
+./bin/start-cluster.sh
+```
+
+Step.3 Start the flink SQL client.
+
+We've created a separate `flink-runtime` module in iceberg project to generate a bundled jar, which could be loaded by flink SQL client directly.
+
+If we want to build the `flink-runtime` bundled jar manually, please just build the `iceberg` project and it will generate the jar under `<iceberg-root-dir>/flink-runtime/build/libs`. Of course, we could also download the `flink-runtime` jar from the [apache official repository](https://repo.maven.apache.org/maven2/org/apache/iceberg/iceberg-flink/).
+
+Step.4 Start the flink SQL client:
+
+```bash
+# HADOOP_HOME is your hadoop root directory after unpack the binary package.
+export HADOOP_CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath`
+
+./bin/sql-client.sh embedded -j <flink-runtime-directory>/iceberg-flink-runtime-xxx.jar shell
+```
+
+By default, iceberg has included hadoop jars for hadoop catalog. If we want to use hive catalog, we will need to load the hive jars when opening the flink sql client. Fortunately, apache flink has provided a [bundled hive jar](https://ci.apache.org/projects/flink/flink-docs-stable/dev/table/hive/#using-bundled-hive-jar) for sql client. So we could open the sql client
+as the following:
+
+```bash
+# HADOOP_HOME is your hadoop root directory after unpack the binary package.
+export HADOOP_CLASSPATH=`$HADOOP_HOME/bin/hadoop classpath`
+
+
+# wget the flink-sql-connector-hive-2.3.6_2.11-1.11.0.jar from the above bundled jar URL firstly.
+
+# open the SQL client.
+./bin/sql-client.sh embedded \
+ -j <flink-runtime-directory>/iceberg-flink-runtime-xxx.jar \
+ -j <hive-bundlded-jar-directory>/flink-sql-connector-hive-2.3.6_2.11-1.11.0.jar \
+ shell
+```
+
+## Creating catalogs and using catalogs.
+
+Flink 1.11 support to create catalogs by using flink sql.
+
+This creates an iceberg catalog named `hive_catalog` that loads tables from a hive metastore:
+
+```sql
+create catalog hive_catalog with(
+ 'type'='iceberg',
+ 'catalog-type'='hive',
+ 'uri'='thrift://localhost:9083',
+ 'clients'='1',
+ 'property-version'='1'
+);
+```
+
+Iceberg also supports a directory-based catalog in HDFS that can be configured using `'catalog-type'='hadoop'`:
+
+```sql
+create catalog hadoop_catalog with(
+ 'type'='iceberg',
+ 'catalog-type'='hadoop',
+ 'warehouse'='hdfs://nn:8020/warehouse/path',
+ 'property-version'='1'
+);
+```
+
+We could execute the sql command `use catalog hive_catalog` to use one of the catalog.
+
+## DDL commands
+
+### `CREATE DATABASE`
+
+By default, iceberg will use the `default` database in flink. Using the following example to create a separate database:
+
+```sql
+CREATE DATABASE iceberg_db;
+USE iceberg_db;
+```
+
+### `CREATE TABLE`
+
+```sql
+CREATE TABLE hive_catalog.default.sample (
+ id BIGINT COMMENT 'unique id',
+ data STRING
+);
+```
+
+Table create commands support most common [flink create clauses](https://ci.apache.org/projects/flink/flink-docs-release-1.11/dev/table/sql/create.html#create-table) now, including:
+
+* `PARTITION BY (column1, column2, ...)` to configure partitioning.
+* `COMMENT 'table document'` to set a table description.
+* `WITH ('key'='value', ...)` to set [table configuration](../configuration)
+
+Currently, it does not support computed column, primary key and watermark definition etc.
+
+### `PARTITIONED BY`
+
+To create a partition table, use `PARTITIONED BY`:
+
+```sql
+CREATE TABLE hive_catalog.default.sample (
+ id BIGINT COMMENT 'unique id',
+ data STRING
+) PARTITIONED BY (data);
+```
+
+Apache Iceberg support hidden partition but apache flink don't support partitioning by a function on columns, so we've no way to support hidden partition in flink DDL now, we will improve apache flink DDL in future.
+
+### `ALTER TABLE`
+
+Iceberg only support altering table properties in flink 1.11 now.
+
+```sql
+ALTER TABLE hive_catalog.default.sample SET ('write.format.default'='avro')
Review comment:
https://issues.apache.org/jira/browse/FLINK-19062 There is a ticket for tracking this.
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