fix: auto-detect schema from dump file header for plan/apply (#296) by tianzhou · Pull Request #312 · pgplex/pgschema

tianzhou · 2026-02-22T07:04:09Z

Summary

Dump output now includes -- Dumped from schema: <name> metadata in the header
Plan and apply commands auto-detect the target schema from this header when --schema is not explicitly set
Prevents accidental cross-schema operations (e.g., dumping vehicle schema then applying without --schema vehicle would previously default to public and drop public tables)

Fixes #296

Changes

internal/dump/formatter.go: Added -- Dumped from schema: <name> line to dump header
cmd/util/schema_detect.go: New utility to parse schema name from dump file header
cmd/plan/plan.go: Auto-detect schema from file when --schema is not explicitly set
cmd/apply/apply.go: Same auto-detection for apply command
internal/diff/header.go: Removed dead GenerateDumpHeader function (duplicate of formatter's method)
cmd/dump/dump_integration_test.go: Updated test normalization to handle new header line

Behavior

If --schema is explicitly set, it is always used (no change)
If --schema is not set and the dump file has -- Dumped from schema: X, uses X
If --schema is not set and the dump file has no schema header (old format), defaults to public (backward compatible)
Auto-detection prints a message to stderr: Auto-detected schema 'vehicle' from dump file

Test plan

Unit tests for schema detection utility (cmd/util/schema_detect_test.go)
Dump integration tests pass (Employee, TenantSchemas)
All diff tests pass (TestDiffFromFiles)
Integration tests pass (TestPlanAndApply — create_table, migrate, dependency categories)
Full CI test suite

🤖 Generated with Claude Code

When dumping a non-public schema (e.g., vehicle), the dump output now includes a "-- Dumped from schema: <name>" metadata line. The plan and apply commands read this header and auto-detect the target schema when --schema is not explicitly set, preventing accidental cross-schema operations that could drop tables from the wrong schema. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

greptile-apps · 2026-02-22T07:06:46Z

Greptile Summary

Adds schema auto-detection to prevent accidental cross-schema operations by embedding schema metadata in dump headers and parsing it during plan/apply commands.

Added -- Dumped from schema: <name> metadata line to dump file headers
Created new utility (cmd/util/schema_detect.go) to parse schema from dump headers by scanning first 20 lines
Modified plan and apply commands to auto-detect schema when --schema flag is not explicitly set
Maintains backward compatibility: defaults to public schema when header is missing (old dump format)
Removed duplicate GenerateDumpHeader function from internal/diff/header.go
Updated test normalization to filter out new schema header line for cross-version comparisons

Confidence Score: 5/5

This PR is safe to merge with minimal risk
Well-designed feature with comprehensive unit tests, clean implementation, proper backward compatibility, and clear separation of concerns
No files require special attention

Important Files Changed

Filename	Overview
cmd/util/schema_detect.go	New utility to parse schema from dump file header, well-tested and straightforward
cmd/plan/plan.go	Added schema auto-detection logic, cleanly implemented with proper flag checking
cmd/apply/apply.go	Added schema auto-detection logic, mirrors plan.go implementation
internal/dump/formatter.go	Added schema metadata line to dump header for auto-detection

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[dump command] -->|writes| B[SQL file with schema header]
    B -->|"-- Dumped from schema: X"| C{plan/apply command}
    C -->|--schema flag set?| D[Use explicit schema]
    C -->|--schema NOT set| E[DetectSchemaFromFile]
    E -->|header found| F[Use detected schema X]
    E -->|header NOT found| G[Default to 'public']
    F --> H[Execute plan/apply with schema X]
    D --> H
    G --> H

_{Last reviewed commit: 8cb2e74}

Copilot

Pull request overview

This PR adds schema metadata to pgschema dump output and uses it to auto-select the correct target schema during plan/apply when --schema isn’t explicitly provided, preventing accidental operations against the default public schema.

Changes:

Add -- Dumped from schema: <name> to the dump header.
Introduce a schema-detection utility that parses the schema from a dump file header.
Update plan and apply to use the detected schema when --schema is not set, and adjust dump integration test normalization accordingly.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
internal/dump/formatter.go	Emits schema metadata in the dump header for downstream consumers.
cmd/util/schema_detect.go	Adds a small helper to detect schema from the dump header.
cmd/util/schema_detect_test.go	Adds unit tests for schema header parsing.
cmd/plan/plan.go	Uses detected schema (when available) as the effective schema for planning.
cmd/apply/apply.go	Uses detected schema (when available) as the effective schema for apply.
internal/diff/header.go	Removes the old dump header generator (now unused).
cmd/dump/dump_integration_test.go	Updates normalization to ignore the new schema header line in comparisons.

Comments suppressed due to low confidence (1)

internal/diff/header.go:2

This file is now empty (only a package declaration). Since GenerateDumpHeader was removed, consider deleting the file entirely to avoid a confusing empty source file in the diff package.

package diff

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Copilot · 2026-02-22T07:08:24Z

cmd/util/schema_detect_test.go

+			name: "quoted schema name",
+			content: `--
+-- pgschema database dump
+--
+
+-- Dumped from database version PostgreSQL 17.7
+-- Dumped by pgschema version 1.7.1
+-- Dumped from schema: my_schema
+
+`,
+			expected: "my_schema",
+		},


This test case is labeled "quoted schema name" but the content uses an unquoted identifier (my_schema). Rename the case to reflect what it actually covers, or update the fixture to include a truly quoted schema name (e.g., "MySchema") and assert the intended behavior.

Copilot · 2026-02-22T07:08:25Z

cmd/util/schema_detect.go

+func detectSchemaFromReader(r io.Reader) (string, error) {
+	scanner := bufio.NewScanner(r)
+	for i := 0; i < 20 && scanner.Scan(); i++ {
+		line := scanner.Text()
+		if strings.HasPrefix(line, schemaHeaderPrefix) {
+			return strings.TrimSpace(line[len(schemaHeaderPrefix):]), nil
+		}
+	}
+	return "", scanner.Err()


detectSchemaFromReader uses bufio.Scanner without increasing the buffer size. Scanner will return ErrTooLong if it encounters a line >64K, which can happen in SQL files (e.g., large function bodies or comments on a single line), causing schema detection to error. Consider increasing the scanner buffer (scanner.Buffer) or using a bufio.Reader to read lines so header parsing is robust.

Copilot · 2026-02-22T07:08:25Z

cmd/plan/plan.go

+	// Auto-detect schema from dump file if --schema was not explicitly set
+	effectiveSchema := planSchema
+	if !cmd.Flags().Changed("schema") && planFile != "" {
+		if detected, err := util.DetectSchemaFromFile(planFile); err == nil && detected != "" {
+			effectiveSchema = detected
+			fmt.Fprintf(os.Stderr, "Auto-detected schema '%s' from dump file\n", detected)
+		}
+	}


Schema auto-detection ignores errors from DetectSchemaFromFile. If header parsing fails (e.g., due to a scanning error), this silently falls back to the default schema, which undermines the safety goal of preventing cross-schema operations. Consider surfacing a warning to stderr when err != nil, or failing fast with a message instructing the user to pass --schema explicitly.

Copilot · 2026-02-22T07:08:25Z

cmd/apply/apply.go

+		if detected, err := util.DetectSchemaFromFile(applyFile); err == nil && detected != "" {
+			effectiveSchema = detected
+			fmt.Fprintf(os.Stderr, "Auto-detected schema '%s' from dump file\n", detected)
+		}


Schema auto-detection ignores errors from DetectSchemaFromFile. If header parsing fails, apply will silently continue using the default schema, which can reintroduce the cross-schema risk this change is meant to prevent. Consider warning on detection errors or requiring --schema when detection fails.

Suggested change

if detected, err := util.DetectSchemaFromFile(applyFile); err == nil && detected != "" {

effectiveSchema = detected

fmt.Fprintf(os.Stderr, "Auto-detected schema '%s' from dump file\n", detected)

}

detected, err := util.DetectSchemaFromFile(applyFile)

if err != nil {

return fmt.Errorf("failed to auto-detect schema from dump file %q: %w (please specify --schema explicitly)", applyFile, err)

}

if detected == "" {

return fmt.Errorf("schema could not be auto-detected from dump file %q; please specify --schema explicitly", applyFile)

}

effectiveSchema = detected

fmt.Fprintf(os.Stderr, "Auto-detected schema '%s' from dump file\n", detected)

tianzhou · 2026-02-22T07:14:08Z

Closing this PR — after further analysis, the reported behavior is working as designed.

pgschema produces schema-agnostic dumps by design. The same dump file can be applied to any schema (public, tenant1, vehicle, etc.). This means --schema must be specified on plan and apply when targeting non-public schemas.

The issue was a missing --schema vehicle flag on the apply command. See the comment on #296 for details.

Copilot AI review requested due to automatic review settings February 22, 2026 07:04

Copilot started reviewing on behalf of tianzhou February 22, 2026 07:04 View session

Copilot AI reviewed Feb 22, 2026

View reviewed changes

tianzhou closed this Feb 22, 2026

tianzhou deleted the fix/issue-296-schema-auto-detect branch February 22, 2026 07:14

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Comments

fix: auto-detect schema from dump file header for plan/apply (#296)#312

fix: auto-detect schema from dump file header for plan/apply (#296)#312
tianzhou wants to merge 1 commit intomainfrom
fix/issue-296-schema-auto-detect

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tianzhou commented Feb 22, 2026

Summary

Changes

Behavior

Test plan

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greptile-apps bot commented Feb 22, 2026

Greptile Summary

Confidence Score: 5/5

Important Files Changed

Flowchart

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