The causes and solutions for PostgreSQL's inability to view data in tables

1. The recovery is not completely successful

• reason: The database recovery process may not be completely successful, resulting in the presence of the table structure but the data is lost.
• Solution：
  1. Check the recovery log to confirm whether the recovery process is successful.
  2. Try to restore the database again to ensure that the backup file is complete and the recovery command is correct.
  3. usepg_restoreorpsqlWhen recovering, add--verboseView detailed logs for parameters:

pg_restore --verbose -U <username> -d <database> <backup_file>

2. Restored to the wrong database

• reason: The data may be restored to the wrong database during recovery, resulting in no data in the currently connected database.
• Solution：

Confirm that the currently connected database is correct:

SELECT current_database();

If the database is wrong, switch to the correct database:

\c <correct_database>

3. Table permissions issue

• reason: The current user does not have permission to access data in the table.
• Solution：

Check the permissions of the current user:

\z <table_name>

If the permissions are insufficient, grant the user access:

GRANT SELECT ON <table_name> TO <username>;

4. Table data is deleted or cleared

• reason: After recovery, the table data may be accidentally deleted or cleared.
• Solution：

Check whether there is data in the table:

SELECT COUNT(*) FROM <table_name>;

If data is lost, try to restore it again from the backup file.

5. The --schema-only parameter was used during recovery

• reason: It may have been used during recovery--schema-onlyParameters, resulting in only the table structure being restored without data.
• Solution：
  1. Check the recovery command to make sure it is not used--schema-onlyParameters.
  2. Restore the database to ensure that the data is also restored.

6. Tables are locked or occupied by other processes

• reason: The table may be locked or occupied by other processes, resulting in the inability to query data.
• Solution：

Check for locked tables:

SELECT * FROM pg_locks WHERE relation = '<table_name>'::regclass;

If the table is locked, terminate the relevant process:

SELECT pg_terminate_backend(<pid>);

7. DBeaver configuration issues

• reason: DBeaver may have filters or restrictions configured, resulting in data being unable to be queried.
• Solution：
  1. Check DBeaver's query settings to make sure that row limits or filters are not enabled.
  2. Try to usepsqlOr other tools query data to confirm whether it is a DBeaver problem.

8. Database corruption

• reason: The database file may be corrupt, causing the data to be inaccessible.
• Solution：

usepg_amcheckorpg_verifybackupCheck database integrity:

pg_amcheck <database_name>

If the database is corrupted, try to restore it again from the backup file.

9. Table data is encrypted or compressed

• reason: Table data may be encrypted or compressed, resulting in the inability to directly query.
• Solution：

  Check whether the table uses encryption or compression.

  If so, use the corresponding decryption or decompression tool to process the data.

10. Table data is partitioned or sliced

• reason: The table may be partitioned or sharded, resulting in the inability to see all data during query.
• Solution：

Check whether the table is a partition table:

SELECT * FROM pg_partitioned_table WHERE partrelid = '<table_name>'::regclass;

If it is a partition table, query the data of all partitions:

SELECT * FROM <table_name> PARTITION (<partition_name>);

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