What causes "reading SHOW CREATE TABLE %s: %w" in gastownhall/beads?

Confirm the table still exists before calling (or re-run the repair, which re-checks presence).

reading SHOW CREATE TABLE %s: %w

Error message

reading SHOW CREATE TABLE %s: %w

What it means

Wraps a failure to run and read SHOW CREATE TABLE for a table. This is the only way Dolt exposes generated-column shape — INFORMATION_SCHEMA.COLUMNS returns EXTRA and GENERATION_EXPRESSION empty for generated columns — so wispDepHasStoredGeneratedDependsOnID depends on it. Thrown when the query fails or the row cannot be scanned (e.g., the table does not exist at call time).

Source

Thrown at internal/storage/schema/migration_repairs.go:745

	if err := db.QueryRowContext(ctx, `
		SELECT COUNT(*) FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
		WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND CONSTRAINT_NAME = ?
	`, table, constraint).Scan(&count); err != nil {
		return false, fmt.Errorf("checking constraint %s on %s: %w", constraint, table, err)
	}
	return count > 0, nil
}

// schemaShowCreateTable returns a table's CREATE statement. It is the only
// place Dolt exposes generated-column shape: INFORMATION_SCHEMA.COLUMNS returns
// EXTRA and GENERATION_EXPRESSION empty for a generated column, and IS_GENERATED
// does not exist there at all.
func schemaShowCreateTable(ctx context.Context, db DBConn, table string) (string, error) {
	var name, ddl string
	// table is a package constant, never caller input; SHOW CREATE TABLE takes
	// no placeholders.
	if err := db.QueryRowContext(ctx, "SHOW CREATE TABLE `"+table+"`").Scan(&name, &ddl); err != nil {
		return "", fmt.Errorf("reading SHOW CREATE TABLE %s: %w", table, err)
	}
	return ddl, nil
}

// schemaColumnInPrimaryKey reports whether column is (one of) table's PRIMARY
// KEY column(s) specifically -- distinct from schemaHasPrimaryKey, which only
// says a primary key exists without saying which column(s) it covers.
func schemaColumnInPrimaryKey(ctx context.Context, db DBConn, table, column string) (bool, error) {
	var count int
	if err := db.QueryRowContext(ctx, `
		SELECT COUNT(*) FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
		WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = ? AND COLUMN_NAME = ? AND CONSTRAINT_NAME = 'PRIMARY'
	`, table, column).Scan(&count); err != nil {
		return false, err
	}
	return count > 0, nil
}

View on GitHub (pinned to 71377f2769)

Solutions

Confirm the table still exists before calling (or re-run the repair, which re-checks presence).
Inspect the wrapped driver error; restore connectivity if the server is down.
If the table genuinely does not exist and the repair expected it, determine whether a prior migration step already replaced it — re-running the repair flow should take the correct branch.
Check Dolt server version supports SHOW CREATE TABLE output with generated-column expression.

Defensive patterns

Strategy: validation

Validate before calling

// ensure the table exists before asking for its DDL
exists, err := schemaTableExists(ctx, db, table)
if err != nil || !exists { /* skip SHOW CREATE TABLE path */ }

Type guard

func isMissingTableErr(err error) bool {
    return strings.Contains(err.Error(), "doesn't exist") || strings.Contains(err.Error(), "not found")
}

Try / catch

ddl, err := schemaShowCreateTable(ctx, db, table)
if err != nil {
    if isMissingTableErr(err) { return nil /* table already replaced/dropped */ }
    return err
}

Prevention

Always check table existence before SHOW CREATE TABLE
Avoid concurrent migrations that drop/rename the same table
Run within a single migration session so the table cannot disappear mid-check
Use a Dolt version that reports generated-column shape in SHOW CREATE TABLE

When it happens

Trigger: SHOW CREATE TABLE `<table>` errors: the table was dropped between the existence check and this call, the server is down, or the Scan into (name, ddl) fails because no row was returned.

Common situations: Race where a concurrent migration drops/renames the table mid-repair; querying a database where the table never existed because the caller skipped the presence check; connection failure.

Related errors

AI-assisted analysis of gastownhall/beads@71377f2769 (2026-08-30). Data as JSON: /api/errors/bca2ed949fe911fc. Report an issue: GitHub.