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Features and limits

Last Updated: Nov 27, 2017

This document lists the basic features and limits of ApsaraDB HybridDB for PostgreSQL.

Features

  • Covers the core functions of Greenplum Database. For details, see Summary of Greenplum Features.

  • Supports MetaScan and SortKey.

  • Supports the ORCA optimizer.

  • Supports distributed stored procedures in PL/PGSQL and PL/JAVA.

  • Supports multiple extensions, such as PostGIS, MADlib, fuzzystrmatch, orafunc, pgcrypto, and intarray. (You can use the CREATE EXTENSION command to create them.)

  • Supports using OSS_EXT extension to read data from or write data to Alibaba Cloud OSS (Object Storage Service), and supports the gzip compression to reduce the external table storage cost.

  • Supports the JSON data type and the HyperLogLog type. (You can use the CREATE EXTENSION command to create them.)

Limits

  • For limits of the core functions, see Summary of Greenplum Features.

  • Permission limits: The initial user of HybridDB for PostgreSQL (the root user) has the permission for creating databases (CREATEDB) and users (CREATEROLE), but does not have the super user permission (SUPERUSER). That is,

    • The root user cannot perform operations requiring the super user permission. For example, the root user cannot run file functions such as pg\_ls\_dir.

    • The root user has the permission to view and modify the data of all other non-super users, and terminate (Kill) the connections of other non-super users.

  • Not support the PL/R and PL/Java extensions.

  • Supports creating the PL/Python extensions, but does not support creating functions by using PL/Python.

  • Not support the gpfdist tool.

  • Not support MapReduce interfaces, gphdfs storage interfaces and local external tables.

  • Not support automatic backup and recovery. HybridDB for PostgreSQL keeps two copies of data, and you can back up data by using the pg_dump tool.

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