XMover: Fix system-schema filter in active-shards command: 'gc' schema not properly excluded

[coderabbitai]

Problem

The system-schema filter in the active-shards command has a bug that prevents proper exclusion of system tables under the gc schema.

Current Code (Line ~319-330 in cratedb_toolkit/admin/xmover/cli.py)

if exclude_system:
    snapshots = [
        s
        for s in snapshots
        if not (
            s.schema_name.startswith("gc.")  # ❌ This won't match "gc" schema
            or s.schema_name == "information_schema"
            or s.schema_name == "sys"
            or s.table_name.endswith("_events")
            or s.table_name.endswith("_log")
        )
    ]

Issue

s.schema_name.startswith("gc.") looks for schemas starting with "gc." (with dot), but the actual schema name is "gc" (without dot). This means:

• "gc".startswith("gc.") returns False
• System tables under the gc schema won't be excluded as intended

Evidence

From test file tests/admin/test_active_shard_monitor.py:

self.create_test_snapshot("gc", "scheduled_jobs_log", 0, "data-hot-8", True, 15876, 100.0)

The help text also suggests this intent:

@click.option("--exclude-system", is_flag=True, help="Exclude system tables (gc.*, information_schema.*)")

Suggested Fix

if exclude_system:
    system_schemas = {"gc", "information_schema", "sys"}
    snapshots = [
        s for s in snapshots
        if s.schema_name not in system_schemas
        and not (s.table_name.endswith("_events") or s.table_name.endswith("_log"))
    ]

Or if there are indeed sub-schemas under gc:

if exclude_system:
    snapshots = [
        s for s in snapshots
        if not (
            (s.schema_name == "gc" or s.schema_name.startswith("gc."))
            or s.schema_name == "information_schema"
            or s.schema_name == "sys"
            or s.table_name.endswith("_events")
            or s.table_name.endswith("_log")
        )
    ]

Backlinks

• PR: Admin/XMover: Add CrateDB shard analyzer and movement tool #523
• Comment: Admin/XMover: Add CrateDB shard analyzer and movement tool #523 (comment)
• Requested by: @amotl

Please review and confirm the expected behavior for system schema filtering.

[amotl]

@coderabbitai: Can you please transfer or replicate this ticket into the cratedb-xlens project, then close this issue?

[coderabbitai]

Replicated to crate-workbench/cratedb-xlens as requested by @amotl. Closing this issue.

[coderabbitai]

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🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Step 1: Create new issue in crate-workbench/cratedb-xlens
gh issue create \
  --repo crate-workbench/cratedb-xlens \
  --title "XMover: Fix system-schema filter in active-shards command: 'gc' schema not properly excluded" \
  --body "## Problem

The system-schema filter in the \`active-shards\` command has a bug that prevents proper exclusion of system tables under the \`gc\` schema.

## Current Code (Line ~319-330 in cratedb_toolkit/admin/xmover/cli.py)

\`\`\`python
if exclude_system:
    snapshots = [
        s
        for s in snapshots
        if not (
            s.schema_name.startswith(\"gc.\")  # ❌ This won't match \"gc\" schema
            or s.schema_name == \"information_schema\"
            or s.schema_name == \"sys\"
            or s.table_name.endswith(\"_events\")
            or s.table_name.endswith(\"_log\")
        )
    ]
\`\`\`

## Issue

\`s.schema_name.startswith(\"gc.\")\` looks for schemas starting with \`\"gc.\"\` (with dot), but the actual schema name is \`\"gc\"\` (without dot). This means:
- \`\"gc\".startswith(\"gc.\")\` returns \`False\`
- System tables under the \`gc\` schema won't be excluded as intended

## Evidence

From test file \`tests/admin/test_active_shard_monitor.py\`:
\`\`\`python
self.create_test_snapshot(\"gc\", \"scheduled_jobs_log\", 0, \"data-hot-8\", True, 15876, 100.0)
\`\`\`

The help text also suggests this intent:
\`\`\`python
`@click.option`(\"--exclude-system\", is_flag=True, help=\"Exclude system tables (gc.*, information_schema.*)\")
\`\`\`

## Suggested Fix

\`\`\`python
if exclude_system:
    system_schemas = {\"gc\", \"information_schema\", \"sys\"}
    snapshots = [
        s for s in snapshots
        if s.schema_name not in system_schemas
        and not (s.table_name.endswith(\"_events\") or s.table_name.endswith(\"_log\"))
    ]
\`\`\`

Or if there are indeed sub-schemas under gc:
\`\`\`python
if exclude_system:
    snapshots = [
        s for s in snapshots
        if not (
            (s.schema_name == \"gc\" or s.schema_name.startswith(\"gc.\"))
            or s.schema_name == \"information_schema\"
            or s.schema_name == \"sys\"
            or s.table_name.endswith(\"_events\")
            or s.table_name.endswith(\"_log\")
        )
    ]
\`\`\`

## Backlinks

- **Original issue**: https://github.com/crate/cratedb-toolkit/issues/542
- **PR**: https://github.com/crate/cratedb-toolkit/pull/523
- **Comment**: https://github.com/crate/cratedb-toolkit/pull/523#discussion_r2324616269
- **Requested by**: `@amotl`"

# Step 2: Close the original issue `#542` in crate/cratedb-toolkit
gh issue close 542 --repo crate/cratedb-toolkit --comment "Replicated to crate-workbench/cratedb-xlens as requested by `@amotl`. Closing this issue."

Length of output: 194

---

@amotl, both actions are done:

1. Replicated → New issue created at crate-workbench/cratedb-xlens#45 with all the original details, suggested fixes, and backlinks preserved.
2. Closed → The original issue crate/cratedb-toolkit#542 has been closed with a reference to the new issue.