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CREATE BLOB

Enterprise command reference.

Command Snapshot

Field Value
Category DDL and Administration
Mutates Data Yes/Depends
Scope Cluster / Object
Privilege Model Requires DDL/administrative privilege according to target object scope.

Purpose

Defines, changes, or removes schema and metadata objects.

Syntax

CREATE BLOB TABLE table_name
[CLUSTERED INTO num_shards SHARDS]
[ WITH ( storage_parameter [= value] [, ... ] ) ]

Operational Notes

  • Use schema-qualified identifiers in automation and automation pipelines.
  • Validate behavior in staging for cluster-impacting or governance-impacting changes.
  • Confirm runtime effects through system tables and metrics before and after execution.

When to Use

  • Use during planned schema and runtime administration changes.
  • Use in automation pipelines with environment-specific validation and rollback strategy.

When Not to Use

  • Avoid during incident windows unless the command is part of approved mitigation.
  • Avoid schema changes in peak traffic windows without staged rollout.

Common Errors and Troubleshooting

Symptom Likely Cause Action
Permission denied / unauthorized Missing privilege on object or cluster scope Re-run with required grants or elevated admin role.
Analysis/parse error Syntax variant or object shape mismatch Compare with canonical syntax and object definition.
Runtime failure under load Resource limits, breaker pressure, or node state transitions Check sys.jobs, sys.operations, sys.checks, and retry after mitigation.

Cross-References

Detailed Reference

Creates a new table for storing Binary Large Objects (BLOBs) in monkdb.

SQL Statement

CREATE BLOB TABLE table_name
[CLUSTERED INTO num_shards SHARDS]
[ WITH ( storage_parameter [= value] [, ... ] ) ]

Description

The CREATE BLOB TABLE statement creates a dedicated table for storing unstructured binary data (BLOBs). These tables are automatically sharded based on the BLOB's digest (hash) for efficient distribution across nodes.

Clauses

CLUSTERED

Specifies the sharding configuration for the BLOB table:

CLUSTERED INTO num_shards SHARDS
  • num_shards:
  • Type: integer > 0
  • Defines how many shards the BLOB table will be split into.
  • BLOB tables are always sharded by their digest (hash value), not by user-defined columns.

WITH

Configures storage parameters for the BLOB table:

WITH (
    blobs_path = 'path/to/directory',
    number_of_replicas = value
)

Supported parameters:

Parameter Type Default Description
blobs_path text Global config Custom path for BLOB storage (absolute or relative to MONKDB_HOME).
number_of_replicas integer 1 Number of replicas per shard. Set to 0 to disable replication.

Key Parameters

blobs_path

  • Overrides the global BLOB storage path for this table
  • Must be writable by the monkdb system user
  • Example paths:
  • Absolute: /mnt/monkdb_blobs/cust_table_data
  • Relative: custom_blobs (resolves to MONKDB_HOME/custom_blobs)

Examples

Basic BLOB Table

Create a BLOB table with 3 shards and default settings:

CREATE BLOB TABLE my_images
CLUSTERED INTO 3 SHARDS;

Custom Storage Path

Create a BLOB table with dedicated storage location:

CREATE BLOB TABLE audit_logs
CLUSTERED INTO 5 SHARDS
WITH (
    blobs_path = '/var/lib/monkdb/secure_blobs',
    number_of_replicas = 0
);

Additional Operations

Modify Replica Count

ALTER BLOB TABLE my_images SET (number_of_replicas = 1);

Delete BLOB Table

DROP BLOB TABLE my_images;

Notes

  1. Shard Allocation: BLOBs are automatically distributed based on their SHA-1 digest
  2. Access Control: Use the blob schema prefix for queries (e.g., SELECT * FROM blob.my_images)
  3. Backup Limitation: BLOB tables cannot be backed up via monkdb's snapshot/restore functionality
  4. Path Priority: Table-specific blobs_path overrides global configuration
  5. Security: Ensure filesystem permissions match monkdb's runtime user

Permissions

  • DDL Rights: The user must have CREATE privileges in the database to define new BLOB tables.
  • Filesystem Access: The MonkDB process must have write permissions on the directory specified in blobs_path (if used).
  • DROP/ALTER Access: Only the creator or a superuser can alter or drop the BLOB table.

Summary

Feature Supported / Behavior
Stores Binary Data Yes Yes (BLOBs only)
Digest-Based Sharding Yes Automatic using SHA-1
Custom Storage Path Yes via blobs_path
Replication Yes Configurable via number_of_replicas
Column Definitions No Not supported (binary content only)
Accessible via blob schema Yes Yes
Included in Backups No No
Requires CREATE Privilege Yes Yes
Per-Table Storage Path Isolation Yes Optional via WITH (blobs_path = ...)