[Bug]: Explain Plan does not work for Postgres

[GiteshDohare]

Describe the bug

When I try to use "Explain Plan" with Postgres Database i get this error
Explain query failed: error deserializing column 0

Works fine on MySQL and SQLite, Does not work for Postgres (tested with Postgres v16 and v18)

To Reproduce

use Explain Plan feature with any query in Postgres

OS Version

Ubuntu 24.04, Windows 10

Tabularis Version

v0.12.0

Relevant Log Output

[Logger] Capturing logger initialized successfully with level: Info
[LOG] [2026-06-03 11:53:41.153] [INFO] tabularis_lib - Tabularis application starting...
[LOG] [2026-06-03 11:53:41.153] [INFO] tabularis_lib - Debug mode enabled - verbose logging active
[LOG] [2026-06-03 11:53:41.211] [WARN] arboard::platform::linux - Tried to initialize the wayland data control protocol clipboard, but failed. Falling back to the X11 clipboard protocol. The error was: Unknown error while interacting with the clipboard: A required Wayland protocol (ext-data-control, or wlr-data-control version 1) is not supported by the compositor
[LOG] [2026-06-03 11:53:41.400] [INFO] tabularis_lib::drivers::registry - Registering driver: MySQL (mysql)
[LOG] [2026-06-03 11:53:41.400] [INFO] tabularis_lib::drivers::registry - Registering driver: PostgreSQL (postgres)
[LOG] [2026-06-03 11:53:41.400] [INFO] tabularis_lib::drivers::registry - Registering driver: SQLite (sqlite)
[LOG] [2026-06-03 11:53:41.401] [INFO] tabularis_lib::ai_approval_watcher - AI approval watcher started on /home/gitesh/.config/tabularis/pending_approvals
[LOG] [2026-06-03 11:53:41.401] [INFO] tabularis_lib::health_check - Health check: starting ping loop with interval 30s
[LOG] [2026-06-03 11:53:41.402] [INFO] tabularis_lib - DevTools opened (debug mode active)
[LOG] [2026-06-03 11:53:44.336] [INFO] tabularis_lib::commands - Testing connection to database: test-db
[Keychain] Getting DB password for 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[Keychain] Password found for 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[Keychain] Getting DB password for 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[Keychain] Password found for 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.362] [INFO] tabularis_lib::commands - Connection test successful for database: test-db
[LOG] [2026-06-03 11:53:44.363] [INFO] tabularis_lib::health_check - Health check: registering connection 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.364] [INFO] tabularis_lib::commands - Fetching schemas for connection: 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.364] [INFO] tabularis_lib::pool_manager - Creating new PostgreSQL connection pool for: postgres@Some("localhost") (key: postgres:conn:235be7ab-2f0f-44fa-a7af-d7c9a05b74ca:test-db)
[LOG] [2026-06-03 11:53:44.365] [INFO] tabularis_lib::pool_manager - PostgreSQL connection pool created successfully for: test-db (key: postgres:conn:235be7ab-2f0f-44fa-a7af-d7c9a05b74ca:test-db)
[LOG] [2026-06-03 11:53:44.387] [INFO] tabularis_lib::commands - Fetching tables for connection: 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.388] [INFO] tabularis_lib::commands - Fetching views for connection: 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.388] [INFO] tabularis_lib::commands - Fetching routines for connection: 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.388] [INFO] tabularis_lib::commands - Fetching triggers for connection: 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca
[LOG] [2026-06-03 11:53:44.392] [INFO] tabularis_lib::commands - Retrieved 1 tables from test-db
[LOG] [2026-06-03 11:53:44.396] [INFO] tabularis_lib::commands - Retrieved 0 views from test-db
[LOG] [2026-06-03 11:53:44.398] [INFO] tabularis_lib::commands - Retrieved 0 triggers
[LOG] [2026-06-03 11:53:57.099] [INFO] tabularis_lib::commands - Explaining query on connection: 235be7ab-2f0f-44fa-a7af-d7c9a05b74ca | analyze: true | Query: SELECT * FROM employees
[LOG] [2026-06-03 11:53:57.107] [ERROR] tabularis_lib::commands - Explain query failed: error deserializing column 0

[debba]

@GiteshDohare Are you able to open a PR for it?

[GiteshDohare]

@GiteshDohare Are you able to open a PR for it?

I would love to help, but I don't have any background or experience in Rust.
I'm worried I might miss project standards, so I'll leave the PR to someone more familiar with the codebase

[debba]

Tracked this down. EXPLAIN (FORMAT JSON) returns the plan in a column typed as json, but the Postgres driver was reading it as a plain String. tokio-postgres won't deserialize a json column into a String, which is exactly the error deserializing column 0 you hit — so the feature never worked on any Postgres version, hence both 16 and 18 failing.

Fix in #279: read the column as a JSON value and feed it to the existing parser (with a text fallback for Postgres-compatible engines). Will land in the next release.

Thanks for the detailed report and logs.