@simonecoelhosfo/optimizely-mcp-server
Version:
Optimizely MCP Server for AI assistants with integrated CLI tools
346 lines • 12.9 kB
JavaScript
/**
* QueryOptimizer - Intelligent query optimization for analytics
*
* Optimizations:
* - Index usage analysis
* - Query rewriting for better performance
* - Join order optimization
* - Predicate pushdown
* - Unnecessary column elimination
* - Query plan caching
*/
import { getLogger } from '../logging/Logger.js';
export class QueryOptimizer {
db;
indexCache = new Map();
statsCache = new Map();
queryPlanCache = new Map();
constructor(database) {
this.db = database;
this.loadIndexInfo();
this.loadTableStats();
}
/**
* Optimize a hybrid query
*/
optimize(query, intent) {
const optimizations = [];
let optimizedQuery = { ...query };
let estimatedCost = 100; // Base cost
// 1. Analyze current query plan
const queryPlan = this.analyzeQueryPlan(query.sql);
// 2. Check if we can use cached results
const cacheEligible = this.checkCacheEligibility(query, intent);
if (cacheEligible) {
optimizations.push({
type: 'cache',
description: 'Query eligible for caching',
impact: 'high'
});
}
// 3. Optimize column selection
const columnOpt = this.optimizeColumnSelection(optimizedQuery, intent);
if (columnOpt.optimized) {
optimizedQuery = columnOpt.query;
optimizations.push(...columnOpt.optimizations);
estimatedCost *= 0.8; // 20% improvement
}
// 4. Optimize filters and indexes
const filterOpt = this.optimizeFilters(optimizedQuery, queryPlan);
if (filterOpt.optimized) {
optimizedQuery = filterOpt.query;
optimizations.push(...filterOpt.optimizations);
estimatedCost *= filterOpt.costReduction;
}
// 5. Optimize joins
const joinOpt = this.optimizeJoins(optimizedQuery);
if (joinOpt.optimized) {
optimizedQuery = joinOpt.query;
optimizations.push(...joinOpt.optimizations);
estimatedCost *= joinOpt.costReduction;
}
// 6. Add query hints
const hintOpt = this.addQueryHints(optimizedQuery, queryPlan);
if (hintOpt.optimized) {
optimizedQuery = hintOpt.query;
optimizations.push(...hintOpt.optimizations);
}
getLogger().debug({
originalSQL: query.sql,
optimizedSQL: optimizedQuery.sql,
optimizationCount: optimizations.length,
estimatedCost,
cacheEligible
}, 'QueryOptimizer: Query optimized');
return {
optimizedQuery,
optimizations,
estimatedCost,
useCache: cacheEligible
};
}
/**
* Load index information from database
*/
loadIndexInfo() {
try {
const tables = this.db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'").all();
for (const { name: table } of tables) {
const indexes = this.db.prepare("SELECT name, sql FROM sqlite_master WHERE type='index' AND tbl_name=?").all(table);
const indexInfo = [];
for (const index of indexes) {
// Parse index columns from SQL
const columnMatch = index.sql?.match(/\((.*?)\)/);
if (columnMatch) {
const columns = columnMatch[1]
.split(',')
.map(col => col.trim().replace(/["'`]/g, ''));
indexInfo.push({
table,
name: index.name,
columns,
unique: index.sql.includes('UNIQUE')
});
}
}
this.indexCache.set(table, indexInfo);
}
getLogger().debug({
tableCount: tables.length,
totalIndexes: Array.from(this.indexCache.values()).flat().length
}, 'QueryOptimizer: Loaded index information');
}
catch (error) {
getLogger().warn({ error: error.message }, 'QueryOptimizer: Failed to load indexes');
}
}
/**
* Load table statistics
*/
loadTableStats() {
try {
const tables = this.db.prepare("SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'").all();
for (const { name: table } of tables) {
try {
const countResult = this.db.prepare(`SELECT COUNT(*) as count FROM ${table}`).get();
const indexes = this.indexCache.get(table) || [];
this.statsCache.set(table, {
table,
rowCount: countResult.count,
hasIndex: indexes.length > 0,
indexedColumns: indexes.flatMap(idx => idx.columns)
});
}
catch (error) {
// Table might not be accessible
continue;
}
}
}
catch (error) {
getLogger().warn({ error: error.message }, 'QueryOptimizer: Failed to load table stats');
}
}
/**
* Analyze query execution plan
*/
analyzeQueryPlan(sql) {
const cacheKey = sql;
// Check cache first
const cached = this.queryPlanCache.get(cacheKey);
if (cached)
return cached;
try {
const plan = this.db.prepare(`EXPLAIN QUERY PLAN ${sql}`).all();
const planText = JSON.stringify(plan);
// Cache the plan
this.queryPlanCache.set(cacheKey, planText);
return planText;
}
catch (error) {
return '';
}
}
/**
* Check if query is eligible for caching
*/
checkCacheEligibility(query, intent) {
// Don't cache if:
// - Query modifies data
// - Query uses time-sensitive functions
// - Result set is expected to be very large
const sql = query.sql.toLowerCase();
if (sql.includes('insert') || sql.includes('update') || sql.includes('delete')) {
return false;
}
if (sql.includes('datetime(') || sql.includes('date(') || sql.includes('now(')) {
return false;
}
// Check expected result size
if (intent?.limit && intent.limit > 1000) {
return false;
}
return true;
}
/**
* Optimize column selection
*/
optimizeColumnSelection(query, intent) {
const optimizations = [];
let optimized = false;
// If using SELECT *, try to optimize to specific columns
if (query.sql.includes('SELECT *') && intent?.jsonPaths) {
// Extract required columns from JSONPaths
const requiredColumns = new Set();
intent.jsonPaths.forEach(path => {
const parts = path.split('.');
if (parts.length > 0) {
requiredColumns.add(parts[0]);
}
});
if (requiredColumns.size > 0 && requiredColumns.size < 10) {
// Replace SELECT * with specific columns
const columns = Array.from(requiredColumns).join(', ');
const newSQL = query.sql.replace(/SELECT \*/i, `SELECT ${columns}`);
optimizations.push({
type: 'column_elimination',
description: `Reduced columns from * to ${requiredColumns.size} specific columns`,
impact: 'medium'
});
return {
optimized: true,
query: { ...query, sql: newSQL },
optimizations
};
}
}
return { optimized: false, query, optimizations };
}
/**
* Optimize filters using indexes
*/
optimizeFilters(query, queryPlan) {
const optimizations = [];
let costReduction = 1.0;
// Check if query is using indexes effectively
const isUsingIndex = queryPlan.includes('USING INDEX');
if (!isUsingIndex) {
// Try to rewrite query to use indexes
const whereMatch = query.sql.match(/WHERE\s+(.+?)(?:GROUP|ORDER|LIMIT|$)/i);
if (whereMatch) {
const whereClause = whereMatch[1];
// Find tables in query
const tableMatch = query.sql.match(/FROM\s+(\w+)/i);
if (tableMatch) {
const table = tableMatch[1];
const indexes = this.indexCache.get(table) || [];
// Check if any index columns are in WHERE clause
for (const index of indexes) {
for (const column of index.columns) {
if (whereClause.includes(column)) {
optimizations.push({
type: 'index',
description: `Query can use index ${index.name} on column ${column}`,
impact: 'high'
});
costReduction *= 0.5; // 50% cost reduction
break;
}
}
}
}
}
}
return {
optimized: optimizations.length > 0,
query,
optimizations,
costReduction
};
}
/**
* Optimize join order based on table sizes
*/
optimizeJoins(query) {
const optimizations = [];
let costReduction = 1.0;
// Extract joins from query
const joinPattern = /JOIN\s+(\w+)\s+/gi;
const joins = [];
let match;
while ((match = joinPattern.exec(query.sql)) !== null) {
joins.push(match[1]);
}
if (joins.length > 1) {
// Get table sizes
const tableSizes = joins.map(table => ({
table,
size: this.statsCache.get(table)?.rowCount || Number.MAX_SAFE_INTEGER
}));
// Sort by size (smallest first)
tableSizes.sort((a, b) => a.size - b.size);
// Check if current order is optimal
const currentOrder = joins;
const optimalOrder = tableSizes.map(t => t.table);
if (JSON.stringify(currentOrder) !== JSON.stringify(optimalOrder)) {
optimizations.push({
type: 'join_order',
description: `Reorder joins for better performance: ${optimalOrder.join(' -> ')}`,
impact: 'medium'
});
costReduction *= 0.7; // 30% improvement
}
}
return {
optimized: optimizations.length > 0,
query,
optimizations,
costReduction
};
}
/**
* Add query hints for better execution
*/
addQueryHints(query, queryPlan) {
const optimizations = [];
let newSQL = query.sql;
// Add INDEXED BY hints where beneficial
if (!queryPlan.includes('SCAN TABLE') || !newSQL.includes('INDEXED BY')) {
// Already using indexes efficiently
return { optimized: false, query, optimizations };
}
// Find table scans that could use indexes
const scanMatch = queryPlan.match(/SCAN TABLE (\w+)/);
if (scanMatch) {
const table = scanMatch[1];
const indexes = this.indexCache.get(table) || [];
if (indexes.length > 0) {
// Use first available index as hint
const indexHint = `${table} INDEXED BY ${indexes[0].name}`;
newSQL = newSQL.replace(new RegExp(`\\b${table}\\b`), indexHint);
optimizations.push({
type: 'index',
description: `Added index hint for table ${table}`,
impact: 'low'
});
}
}
return {
optimized: optimizations.length > 0,
query: { ...query, sql: newSQL },
optimizations
};
}
/**
* Clear all caches
*/
clearCache() {
this.queryPlanCache.clear();
this.indexCache.clear();
this.statsCache.clear();
// Reload
this.loadIndexInfo();
this.loadTableStats();
}
}
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