Phoenix connector#
The Phoenix connector allows querying data stored in Apache HBase using Apache Phoenix.
Requirements#
To query HBase data through Phoenix, you need:
Network access from the Trino coordinator and workers to the ZooKeeper servers. The default port is 2181.
A compatible version of Phoenix. There are two versions of this connector to support different Phoenix versions:
The
phoenixconnector is compatible with all Phoenix 4.x versions starting from 4.14.1.The
phoenix5connector is compatible with all Phoenix 5.x versions starting from 5.1.0.
Configuration#
To configure the Phoenix connector, create a catalog properties file
etc/catalog/phoenix.properties with the following contents,
replacing host1,host2,host3 with a comma-separated list of the ZooKeeper
nodes used for discovery of the HBase cluster:
connector.name=phoenix
phoenix.connection-url=jdbc:phoenix:host1,host2,host3:2181:/hbase
phoenix.config.resources=/path/to/hbase-site.xml
The optional paths to Hadoop resource files, such as hbase-site.xml are used
to load custom Phoenix client connection properties.
For HBase 2.x and Phoenix 5.x (5.1.0 or later) use:
connector.name=phoenix5
The following Phoenix-specific configuration properties are available:
Property Name |
Required |
Description |
|---|---|---|
|
Yes |
|
|
No |
Comma-separated list of configuration files (e.g. |
|
No |
Maximum number of HBase scans that will be performed in a single split. Default is 20.
Lower values will lead to more splits in Trino.
Can also be set via session propery |
General configuration properties#
The following table describes general catalog configuration properties for the connector:
Property name |
Description |
Default value |
|---|---|---|
|
Support case insensitive schema and table names. |
|
|
|
|
|
Path to a name mapping configuration file in JSON format that allows Trino to disambiguate between schemas and tables with similar names in different cases. |
|
|
Frequency with which Trino checks the name matching configuration file for changes. |
|
|
Duration for which metadata, including table and column statistics, is cached. |
|
|
Cache the fact that metadata, including table and column statistics, is not available |
|
|
Maximum number of objects stored in the metadata cache |
|
|
Maximum number of statements in a batched execution. Do not change this setting from the default. Non-default values may negatively impact performance. |
|
|
Enable join pushdown. Equivalent catalog
session property is |
|
Case insensitive matching#
When case-insensitive-name-matching is set to true, Trino
is able to query non-lowercase schemas and tables by maintaining a mapping of
the lowercase name to the actual name in the remote system. However, if two
schemas and/or tables have names that differ only in case (such as “customers”
and “Customers”) then Trino fails to query them due to ambiguity.
In these cases, use the case-insensitive-name-matching.config-file catalog
configuration property to specify a configuration file that maps these remote
schemas/tables to their respective Trino schemas/tables:
{
"schemas": [
{
"remote": "CaseSensitiveName",
"mapping": "case_insensitive_1"
},
{
"remote": "cASEsENSITIVEnAME",
"mapping": "case_insensitive_2"
}],
"tables": [
{
"remoteSchema": "CaseSensitiveName",
"remoteTable": "tablex",
"mapping": "table_1"
},
{
"remoteSchema": "CaseSensitiveName",
"remoteTable": "TABLEX",
"mapping": "table_2"
}]
}
Queries against one of the tables or schemes defined in the mapping
attributes are run against the corresponding remote entity. For example, a query
against tables in the case_insensitive_1 schema is forwarded to the
CaseSensitiveName schema and a query against case_insensitive_2 is forwarded
to the cASEsENSITIVEnAME schema.
At the table mapping level, a query on case_insensitive_1.table_1 as
configured above is forwarded to CaseSensitiveName.tablex, and a query on
case_insensitive_1.table_2 is forwarded to CaseSensitiveName.TABLEX.
By default, when a change is made to the mapping configuration file, Trino must
be restarted to load the changes. Optionally, you can set the
case-insensitive-name-mapping.refresh-period to have Trino refresh the
properties without requiring a restart:
case-insensitive-name-mapping.refresh-period=30s
Non-transactional INSERT#
The connector supports adding rows using INSERT statements.
By default, data insertion is performed by writing data to a temporary table.
You can skip this step to improve performance and write directly to the target
table. Set the insert.non-transactional-insert.enabled catalog property
or the corresponding non_transactional_insert catalog session property to
true.
Note that with this property enabled, data can be corrupted in rare cases where exceptions occur during the insert operation. With transactions disabled, no rollback can be performed.
Querying Phoenix tables#
The default empty schema in Phoenix maps to a schema named default in Trino.
You can see the available Phoenix schemas by running SHOW SCHEMAS:
SHOW SCHEMAS FROM phoenix;
If you have a Phoenix schema named web, you can view the tables
in this schema by running SHOW TABLES:
SHOW TABLES FROM phoenix.web;
You can see a list of the columns in the clicks table in the web schema
using either of the following:
DESCRIBE phoenix.web.clicks;
SHOW COLUMNS FROM phoenix.web.clicks;
Finally, you can access the clicks table in the web schema:
SELECT * FROM phoenix.web.clicks;
If you used a different name for your catalog properties file, use
that catalog name instead of phoenix in the above examples.
Type mapping#
The data type mappings are as follows:
Phoenix |
Trino |
|---|---|
|
(same) |
|
(same) |
|
(same) |
|
(same) |
|
(same) |
|
(same) |
|
|
|
(same) |
|
|
|
(same) |
|
(same) |
|
(same) |
|
(same) |
|
(same) |
The Phoenix fixed length BINARY data type is mapped to the Trino
variable length VARBINARY data type. There is no way to create a
Phoenix table in Trino that uses the BINARY data type, as Trino
does not have an equivalent type.
Decimal type handling#
DECIMAL types with unspecified precision or scale are mapped to a Trino DECIMAL with a default precision of 38 and default scale of 0. The scale can
be changed by setting the decimal-mapping configuration property or the decimal_mapping session property to
allow_overflow. The scale of the resulting type is controlled via the decimal-default-scale
configuration property or the decimal-rounding-mode session property. The precision is always 38.
By default, values that require rounding or truncation to fit will cause a failure at runtime. This behavior
is controlled via the decimal-rounding-mode configuration property or the decimal_rounding_mode session
property, which can be set to UNNECESSARY (the default),
UP, DOWN, CEILING, FLOOR, HALF_UP, HALF_DOWN, or HALF_EVEN
(see RoundingMode).
General configuration properties#
The following properties can be used to configure how data types from the connected data source are mapped to Trino data types and how the metadata is cached in Trino.
Property name |
Description |
Default value |
|---|---|---|
|
Configure how unsupported column data types are handled:
The respective catalog session property is |
|
|
Allow forced mapping of comma separated lists of data types to convert to
unbounded |
Table properties - Phoenix#
Table property usage example:
CREATE TABLE myschema.scientists (
recordkey VARCHAR,
birthday DATE,
name VARCHAR,
age BIGINT
)
WITH (
rowkeys = 'recordkey,birthday',
salt_buckets = 10
);
The following are supported Phoenix table properties from https://phoenix.apache.org/language/index.html#options
Property Name |
Default Value |
Description |
|---|---|---|
|
|
Comma-separated list of primary key columns. See further description below |
|
(none) |
List of keys to presplit the table on. See Split Point. |
|
(none) |
Number of salt buckets for this table. |
|
false |
Whether to disable WAL writes in HBase for this table. |
|
false |
Declares whether this table has rows which are write-once, append-only. |
|
|
Default column family name to use for this table. |
rowkeys#
This is a comma-separated list of columns to be used as the table’s primary key. If not specified, a BIGINT primary key column named ROWKEY is generated
, as well as a sequence with the same name as the table suffixed with _seq (i.e. <schema>.<table>_seq)
, which is used to automatically populate the ROWKEY for each row during insertion.
Table properties - HBase#
The following are the supported HBase table properties that are passed through by Phoenix during table creation.
Use them in the same way as above: in the WITH clause of the CREATE TABLE statement.
Property Name |
Default Value |
Description |
|---|---|---|
|
|
The maximum number of versions of each cell to keep. |
|
|
The minimum number of cell versions to keep. |
|
|
Compression algorithm to use. Valid values are |
|
|
Block encoding algorithm to use. Valid values are: |
|
|
Time To Live for each cell. |
|
|
Bloomfilter to use. Valid values are |
SQL support#
The connector provides read and write access to data and metadata in Phoenix. In addition to the globally available and read operation statements, the connector supports the following features:
SQL DELETE#
If a WHERE clause is specified, the DELETE operation only works if the
predicate in the clause can be fully pushed down to the data source.