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skills/query-expert/scripts/optimize_query.sh

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+#!/bin/bash
+
+# Query Expert - Query Optimizer
+# Analyze and optimize SQL queries
+
+set -e
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+MAGENTA='\033[0;35m'
+NC='\033[0m'
+
+PASS_COUNT=0
+WARN_COUNT=0
+FAIL_COUNT=0
+
+print_success() {
+    echo -e "${GREEN}✓ GOOD${NC} $1"
+    ((PASS_COUNT++))
+}
+
+print_warning() {
+    echo -e "${YELLOW}⚠ IMPROVE${NC} $1"
+    ((WARN_COUNT++))
+}
+
+print_error() {
+    echo -e "${RED}✗ ISSUE${NC} $1"
+    ((FAIL_COUNT++))
+}
+
+print_info() {
+    echo -e "${BLUE}ℹ INFO${NC} $1"
+}
+
+print_section() {
+    echo ""
+    echo -e "${MAGENTA}━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━${NC}"
+    echo -e "${MAGENTA}$1${NC}"
+    echo -e "${MAGENTA}━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━${NC}"
+}
+
+echo ""
+echo "╔════════════════════════════════════════════════════════════╗"
+echo "║                                                            ║"
+echo "║            Query Expert - Query Optimizer                 ║"
+echo "║                                                            ║"
+echo "╚════════════════════════════════════════════════════════════╝"
+echo ""
+
+if [ -z "$1" ]; then
+    print_info "Usage: $0 <query-file.sql>"
+    print_info "Example: $0 slow_query.sql"
+    exit 1
+fi
+
+QUERY_FILE="$1"
+
+if [ ! -f "$QUERY_FILE" ]; then
+    echo -e "${RED}File not found: $QUERY_FILE${NC}"
+    exit 1
+fi
+
+QUERY=$(cat "$QUERY_FILE")
+
+# Section 1: SELECT * Detection
+print_section "1. COLUMN SELECTION"
+
+if echo "$QUERY" | grep -qi "SELECT \*"; then
+    print_error "Using SELECT * (selects all columns)"
+    echo "         Fix: SELECT only needed columns"
+    echo "         SELECT user_id, name, email FROM users;"
+else
+    print_success "Selecting specific columns"
+fi
+
+# Section 2: Index Usage
+print_section "2. INDEX OPPORTUNITIES"
+
+if echo "$QUERY" | grep -qi "WHERE"; then
+    WHERE_COLS=$(echo "$QUERY" | grep -oi "WHERE [^;]*" | grep -o "[a-zA-Z_][a-zA-Z0-9_]*\s*=" | awk '{print $1}')
+    
+    if [ -n "$WHERE_COLS" ]; then
+        print_info "Columns in WHERE clause should have indexes:"
+        for col in $WHERE_COLS; do
+            echo "         CREATE INDEX idx_table_$col ON table($col);"
+        done
+    fi
+fi
+
+if echo "$QUERY" | grep -qi "JOIN.*ON"; then
+    print_info "JOIN columns should have indexes:"
+    echo "         CREATE INDEX idx_table_join_col ON table(join_col);"
+fi
+
+if echo "$QUERY" | grep -qi "ORDER BY"; then
+    print_info "ORDER BY columns benefit from indexes:"
+    echo "         Consider composite index with WHERE + ORDER BY columns"
+fi
+
+# Section 3: JOIN Analysis
+print_section "3. JOIN OPTIMIZATION"
+
+if echo "$QUERY" | grep -qi "LEFT JOIN" && echo "$QUERY" | grep -qi "WHERE"; then
+    print_warning "LEFT JOIN with WHERE on right table"
+    echo "         Consider using INNER JOIN instead"
+fi
+
+if echo "$QUERY" | grep -qi "WHERE.*IN\s*(SELECT"; then
+    print_error "Using IN with subquery"
+    echo "         Fix: Use EXISTS or JOIN instead"
+    echo "         WHERE EXISTS (SELECT 1 FROM ...)"
+fi
+
+# Section 4: Function Usage
+print_section "4. FUNCTION ON COLUMNS"
+
+if echo "$QUERY" | grep -Eqi "WHERE.*(LOWER|UPPER|SUBSTRING|DATE|YEAR|MONTH)\s*\("; then
+    print_error "Function on indexed column in WHERE"
+    echo "         Fix: Use functional index or avoid function"
+    echo "         CREATE INDEX idx_table_lower_col ON table(LOWER(col));"
+fi
+
+# Section 5: DISTINCT Usage
+print_section "5. DISTINCT USAGE"
+
+if echo "$QUERY" | grep -qi "SELECT DISTINCT"; then
+    print_warning "Using DISTINCT (potentially expensive)"
+    echo "         Consider: Is DISTINCT necessary?"
+    echo "         Alternative: Use GROUP BY if aggregating"
+fi
+
+# Section 6: Subqueries
+print_section "6. SUBQUERY OPTIMIZATION"
+
+SUBQUERY_COUNT=$(echo "$QUERY" | grep -oi "SELECT" | wc -l)
+if [ "$SUBQUERY_COUNT" -gt 1 ]; then
+    if echo "$QUERY" | grep -qi "FROM.*SELECT"; then
+        print_info "Contains subqueries - consider CTEs for readability"
+        echo "         WITH cte AS (SELECT ...) SELECT ... FROM cte"
+    fi
+fi
+
+# Section 7: LIMIT Usage
+print_section "7. RESULT SET SIZE"
+
+if ! echo "$QUERY" | grep -qi "LIMIT\|TOP\|FETCH FIRST"; then
+    print_warning "No LIMIT clause found"
+    echo "         Add LIMIT to prevent large result sets"
+    echo "         SELECT ... LIMIT 100;"
+fi
+
+# Section 8: Sorting
+print_section "8. SORTING"
+
+if echo "$QUERY" | grep -qi "ORDER BY"; then
+    if ! echo "$QUERY" | grep -qi "LIMIT"; then
+        print_warning "ORDER BY without LIMIT"
+        echo "         Consider adding LIMIT to reduce sort cost"
+    fi
+fi
+
+# Summary
+echo ""
+echo "╔════════════════════════════════════════════════════════════╗"
+echo "║                  Optimization Summary                      ║"
+echo "╚════════════════════════════════════════════════════════════╝"
+echo ""
+echo -e "${GREEN}✓ Good practices:  $PASS_COUNT${NC}"
+echo -e "${YELLOW}⚠ Improvements:    $WARN_COUNT${NC}"
+echo -e "${RED}✗ Issues found:    $FAIL_COUNT${NC}"
+echo ""
+
+TOTAL=$((PASS_COUNT + FAIL_COUNT + WARN_COUNT))
+if [ $TOTAL -gt 0 ]; then
+    SCORE=$(( ((PASS_COUNT * 2 + WARN_COUNT) * 100) / (TOTAL * 2) ))
+    echo "Query Score: $SCORE%"
+    echo ""
+fi
+
+print_info "Recommended Next Steps:"
+echo "  1. Run EXPLAIN ANALYZE on this query"
+echo "  2. Create recommended indexes"
+echo "  3. Test query performance before/after"
+echo "  4. Monitor query in production"
+echo ""
+
+print_info "EXPLAIN Commands:"
+echo "  PostgreSQL: EXPLAIN ANALYZE <query>"
+echo "  MySQL:      EXPLAIN <query>"
+echo "  MongoDB:    db.collection.find().explain('executionStats')"
+echo ""
+
+[ $FAIL_COUNT -gt 0 ] && exit 1 || exit 0