SHOW Statement Support

HarborSQL handles supported Databricks SHOW statements through a Unity Catalog metadata path. These statements do not run through Apache DataFusion and do not open Delta tables.

For each supported SHOW statement, HarborSQL forwards the Databricks token received from the client to Unity Catalog. The caller sees only metadata that Unity Catalog allows that identity to access.

Supported Statements

SHOW CATALOGS [ [ LIKE ] regex_pattern ]
SHOW SCHEMAS [ { FROM | IN } catalog_name ] [ [ LIKE ] regex_pattern ]
SHOW DATABASES [ { FROM | IN } catalog_name ] [ [ LIKE ] regex_pattern ]
SHOW TABLES [ { FROM | IN } schema_name ] [ [ LIKE ] regex_pattern ]
SHOW VIEWS [ { FROM | IN } schema_name ] [ [ LIKE ] regex_pattern ]
SHOW TABLE EXTENDED [ { IN | FROM } schema_name ] LIKE regex_pattern

SHOW SCHEMAS and SHOW DATABASES are treated as aliases.

Namespace Resolution

If no catalog or schema is specified, HarborSQL uses the catalog and schema from the active Databricks SQL session. For the JSON query endpoint, it uses the request catalog and schema, falling back to HARBORSQL_DEFAULT_CATALOG and HARBORSQL_DEFAULT_SCHEMA.

For table and view discovery:

• SHOW TABLES uses the current catalog and schema.
• SHOW TABLES IN schema_name uses the current catalog and the provided schema.
• SHOW TABLES IN catalog_name.schema_name uses the provided catalog and schema.

SHOW VIEWS and SHOW TABLE EXTENDED follow the same namespace rules.

Pattern Matching

HarborSQL follows Databricks pattern matching for this SHOW subset:

• Matching is case-insensitive.
• Leading and trailing blanks in the pattern are trimmed.
• * matches zero or more characters.
• | separates alternatives.
• Other pattern characters are interpreted as regular expression syntax.

Examples:

SHOW CATALOGS LIKE 'prod*'
SHOW SCHEMAS IN main LIKE 'sales*|finance*'
SHOW TABLES IN main.analytics LIKE 'fact_[a-z]+'

Result Columns

Statement	Columns
SHOW CATALOGS	catalog
SHOW SCHEMAS / SHOW DATABASES	databaseName
SHOW TABLES	database, tableName, isTemporary
SHOW VIEWS	namespace, viewName, isTemporary
SHOW TABLE EXTENDED	database, tableName, isTemporary, information

HarborSQL does not currently create session-local temporary objects, so isTemporary is always false.

Current Limits

SHOW TABLE EXTENDED ... PARTITION (...) is parsed but returns an unsupported SQL error. Partition-specific table metadata requires a separate Delta metadata design.

These statements are not part of the initial SHOW metadata surface:

• SHOW COLUMNS
• SHOW FUNCTIONS
• SHOW GRANTS
• SHOW TBLPROPERTIES
• SHOW CREATE
• SHOW PARTITIONS

Unsupported SHOW syntax returns HarborSQL's stable UNSUPPORTED_SQL client error code.