This topic describes the common errors that you may encounter in using Hologres and how to fix them.
Maximum number of partitions exceeded
Scenario: The following error message appears when you query data in a partitioned table:
ERROR: AXF Exception: specified partitions count in odps table: <project_name.table_name>
is: xxx, exceeds the limitation of xxx, please add stricter partition filter
Cause: To guarantee the query performance, Hologres can scan a maximum of 50 partitions from a partitioned table during a single query.
Workaround: We recommend that you change the data table to be queried to a non-partitioned table or a partitioned table with fewer than 50 partitions before querying data in the table.
Transaction error
Scenario: The following error message appears when you execute an SQL statement:
ERROR: current transaction is aborted, commands ignored until end of transaction block
Cause: A new SQL statement is executed when the previous SQL statement is still in progress.
rollback
command.
I/O error
Scenario: The following error message appears when you execute an SQL statement:
An I/O error occurred while sending to the backbend
Workaround: Refresh the page and re-execute the SQL statement.
DataService Studio or JDBC connection error
Scenario: The following error message appears when you connect to Hologres through DataWorks DataService Studio or Java Database Connectivity (JDBC):
SQL state [XX000]; error code [0]; ERROR: Query could not generate plan by gporca
: GPDB Expression type: Query Parameter not supported in DXL; nested exception is
org.postgresql.util.PSQL
Cause: Required extension parameters are absent in the connection string.
Workaround: Append the required extension parameters to the end of the connection string. The correct connection string is as follows:
jdbc:postgresql://endpoint:port/dbname? preferQueryMode=simple&tcpKeepAlive=true
Error thrown during data query in a foreign table
Scenario: The following error message appears when you query MaxCompute data in a foreign table:
ERROR: Query:[100181047458824706] Get result failed: exec sql failed => status:7 msg:ERROR:
External table size 268911MB exceeded the maximum cache size 102400MB
Cause: Hologres can scan a maximum of 100 GB data from a foreign table during a single query, but the foreign table contains more than 100 GB data.
- Specify filter conditions to filter out unnecessary data and make sure that the amount of data to be scanned does not exceed 100 GB.
- Import the MaxCompute data to Hologres and then query the imported data in Hologres. Hologres does not limit the amount of data to be scanned in itself.