gem-hunter
Language: Python
Postgres MCP Pro provides configurable read/write access and performance analysis for you and your AI agents.
Postgres MCP Pro is an open source Model Context Protocol (MCP) server built to support you and your AI agents throughout the entire development process—from initial coding, through testing and deployment, and to production tuning and maintenance.
Postgres MCP Pro does much more than wrap a database connection.
Features include:
Postgres MCP Pro supports both the Standard Input/Output (stdio) and Server-Sent Events (SSE) transports, for flexibility in different environments.
For additional background on why we built Postgres MCP Pro, see our launch blog post.
From Unusable to Lightning Fast
What we did:
See the video below or read the play-by-play.
Demo-Movie-App.mp4Before getting started, ensure you have:
You can confirm your access credentials are valid by using psql or a GUI tool such as pgAdmin.
The choice to use Docker or Python is yours. We generally recommend Docker because Python users can encounter more environment-specific issues. However, it often makes sense to use whichever method you are most familiar with.
Choose one of the following methods to install Postgres MCP Pro:
Pull the Postgres MCP Pro MCP server Docker image. This image contains all necessary dependencies, providing a reliable way to run Postgres MCP Pro in a variety of environments.
docker pull crystaldba/postgres-mcp
If you have pipx installed you can install Postgres MCP Pro with:
pipx install postgres-mcp
Otherwise, install Postgres MCP Pro with uv:
uv pip install postgres-mcp
If you need to install uv, see the uv installation instructions.
We provide full instructions for configuring Postgres MCP Pro with Claude Desktop. Many MCP clients have similar configuration files, you can adapt these steps to work with the client of your choice.
You will need to edit the Claude Desktop configuration file to add Postgres MCP Pro. The location of this file depends on your operating system:
~/Library/Application Support/Claude/claude_desktop_config.json%APPDATA%/Claude/claude_desktop_config.jsonYou can also use Settings menu item in Claude Desktop to locate the configuration file.
You will now edit the mcpServers section of the configuration file.
{
"mcpServers": {
"postgres": {
"command": "docker",
"args": [
"run",
"-i",
"--rm",
"-e",
"DATABASE_URI",
"crystaldba/postgres-mcp",
"--access-mode=unrestricted"
],
"env": {
"DATABASE_URI": "postgresql://username:password@localhost:5432/dbname"
}
}
}
}The Postgres MCP Pro Docker image will automatically remap the hostname localhost to work from inside of the container.
host.docker.internal automatically172.17.0.1 or the appropriate host address automatically{
"mcpServers": {
"postgres": {
"command": "uvx",
"args": [
"postgres-mcp",
"--access-mode=unrestricted"
],
"env": {
"DATABASE_URI": "postgresql://username:password@localhost:5432/dbname"
}
}
}
}{
"mcpServers": {
"postgres": {
"command": "postgres-mcp",
"args": [
"--access-mode=unrestricted"
],
"env": {
"DATABASE_URI": "postgresql://username:password@localhost:5432/dbname"
}
}
}
}{
"mcpServers": {
"postgres": {
"command": "uv",
"args": [
"run",
"postgres-mcp",
"--access-mode=unrestricted"
],
"env": {
"DATABASE_URI": "postgresql://username:password@localhost:5432/dbname"
}
}
}
}Replace postgresql://... with your Postgres database connection URI.
Postgres MCP Pro supports multiple access modes to give you control over the operations that the AI agent can perform on the database:
To use restricted mode, replace --access-mode=unrestricted with --access-mode=restricted in the configuration examples above.
Many MCP clients have similar configuration files to Claude Desktop, and you can adapt the examples above to work with the client of your choice.
Command Palette to Cursor Settings, then open the MCP tab to access the configuration file.Command Palette to Open Windsurf Settings Page to access the configuration file.goose configure, then select Add Extension.Connect more tools, click + Add new MCP, then add the new configuration.Postgres MCP Pro supports the SSE transport, which allows multiple MCP clients to share one server, possibly a remote server.
To use the SSE transport, you need to start the server with the --transport=sse option.
For example, with Docker run:
docker run -p 8000:8000 \ -e DATABASE_URI=postgresql://username:password@localhost:5432/dbname \ crystaldba/postgres-mcp --access-mode=unrestricted --transport=sse
Then update your MCP client configuration to call the the MCP server.
For example, in Cursor's mcp.json or Cline's cline_mcp_settings.json you can put:
{
"mcpServers": {
"postgres": {
"type": "sse",
"url": "http://localhost:8000/sse"
}
}
}For Windsurf, the format in mcp_config.json is slightly different:
{
"mcpServers": {
"postgres": {
"type": "sse",
"serverUrl": "http://localhost:8000/sse"
}
}
}To enable index tuning and comprehensive performance analysis you need to load the pg_stat_statements and hypopg extensions on your database.
pg_stat_statements extension allows Postgres MCP Pro to analyze query execution statistics.
For example, this allows it to understand which queries are running slow or consuming significant resources.hypopg extension allows Postgres MCP Pro to simulate the behavior of the Postgres query planner after adding indexes.If your Postgres database is running on a cloud provider managed service, the pg_stat_statements and hypopg extensions should already be available on the system.
In this case, you can just run CREATE EXTENSION commands using a role with sufficient privileges:
CREATE EXTENSION IF NOT EXISTS pg_stat_statements; CREATE EXTENSION IF NOT EXISTS hypopg;
If you are managing your own Postgres installation, you may need to do additional work.
Before loading the pg_stat_statements extension you must ensure that it is listed in the shared_preload_libraries in the Postgres configuration file.
The hypopg extension may also require additional system-level installation (e.g., via your package manager) because it does not always ship with Postgres.
Ask:
Check the health of my database and identify any issues.
Ask:
What are the slowest queries in my database? And how can I speed them up?
Ask:
My app is slow. How can I make it faster?
Ask:
Analyze my database workload and suggest indexes to improve performance.
Ask:
Help me optimize this query: SELECT * FROM orders JOIN customers ON orders.customer_id = customers.id WHERE orders.created_at > '2023-01-01';
The MCP standard defines various types of endpoints: Tools, Resources, Prompts, and others.
Postgres MCP Pro provides functionality via MCP tools alone. We chose this approach because the MCP client ecosystem has widespread support for MCP tools. This contrasts with the approach of other Postgres MCP servers, including the Reference Postgres MCP Server, which use MCP resources to expose schema information.
Postgres MCP Pro Tools:
| Tool Name | Description |
|---|---|
list_schemas |
Lists all database schemas available in the PostgreSQL instance. |
list_objects |
Lists database objects (tables, views, sequences, extensions) within a specified schema. |
get_object_details |
Provides information about a specific database object, for example, a table's columns, constraints, and indexes. |
execute_sql |
Executes SQL statements on the database, with read-only limitations when connected in restricted mode. |
explain_query |
Gets the execution plan for a SQL query describing how PostgreSQL will process it and exposing the query planner's cost model. Can be invoked with hypothetical indexes to simulate the behavior after adding indexes. |
get_top_queries |
Reports the slowest SQL queries based on total execution time using pg_stat_statements data. |
analyze_workload_indexes |
Analyzes the database workload to identify resource-intensive queries, then recommends optimal indexes for them. |
analyze_query_indexes |
Analyzes a list of specific SQL queries (up to 10) and recommends optimal indexes for them. |
analyze_db_health |
Performs comprehensive health checks including: buffer cache hit rates, connection health, constraint validation, index health (duplicate/unused/invalid), sequence limits, and vacuum health. |
Postgres MCP Servers
DBA Tools (including commercial offerings)
Postgres Utilities
How is Postgres MCP Pro different from other Postgres MCP servers? There are many MCP servers allow an AI agent to run queries against a Postgres database. Postgres MCP Pro does that too, but also adds tools for understanding and improving the performance of your Postgres database. For example, it implements a version of the Anytime Algorithm of Database Tuning Advisor for Microsoft SQL Server, a modern industrial-strength algorithm for automatic index tuning.
| Postgres MCP Pro | Other Postgres MCP Servers |
|---|---|
| ✅ Deterministic database health checks | ❌ Unrepeatable LLM-generated health queries |
| ✅ Principled indexing search strategies | ❌ Gen-AI guesses at indexing improvements |
| ✅ Workload analysis to find top problems | ❌ Inconsistent problem analysis |
| ✅ Simulates performance improvements | ❌ Try it yourself and see if it works |
Postgres MCP Pro complements generative AI by adding deterministic tools and classical optimization algorithms The combination is both reliable and flexible.
Why are MCP tools needed when the LLM can reason, generate SQL, etc? LLMs are invaluable for tasks that involve ambiguity, reasoning, or natural language. When compared to procedural code, however, they can be slow, expensive, non-deterministic, and sometimes produce unreliable results. In the case of database tuning, we have well established algorithms, developed over decades, that are proven to work. Postgres MCP Pro lets you combine the best of both worlds by pairing LLMs with classical optimization algorithms and other procedural tools.
How do you test Postgres MCP Pro? Testing is critical to ensuring that Postgres MCP Pro is reliable and accurate. We are building out a suite of AI-generated adversarial workloads designed to challenge Postgres MCP Pro and ensure it performs under a broad variety of scenarios.
What Postgres versions are supported? Our testing presently focuses on Postgres 15, 16, and 17. We plan to support Postgres versions 13 through 17.
Who created this project? This project is created and maintained by Crystal DBA.
TBD
You and your needs are a critical driver for what we build. Tell us what you want to see by opening an issue or a pull request. You can also contact us on Discord.
This section includes a high-level overview technical considerations that influenced the design of Postgres MCP Pro.
Developers know that missing indexes are one of the most common causes of database performance issues. Indexes provide access methods that allow Postgres to quickly locate data that is required to execute a query. When tables are small, indexes make little difference, but as the size of the data grows, the difference in algorithmic complexity between a table scan and an index lookup becomes significant (typically O(n) vs O(log n), potentially more if joins on multiple tables are involved).
Generating suggested indexes in Postgres MCP Pro proceeds in several stages:
Identify SQL queries in need of tuning.
If you know you are having a problem with a specific SQL query you can provide it.
Postgres MCP Pro can also analyze the workload to identify index tuning targets.
To do this, it relies on the pg_stat_statements extension, which records the runtime and resource consumption of each query.
A query is a candidate for index tuning if it is a top resource consumer, either on a per-execution basis or in aggregate.
At present, we use execution time as a proxy for cumulative resource consumption, but it may also make sense to look at specifics resources, e.g., the number of blocks accessed or the number of blocks read from disk.
The analyze_query_workload tool focuses on slow queries, using the mean time per execution with thresholds for execution count and mean execution time.
Agents may also call get_top_queries, which accepts a parameter for mean vs. total execution time, then pass these queries analyze_query_indexes to get index recommendations.
Sophisticated index tuning systems use "workload compression" to produce a representative subset of queries that reflects the characteristics of the workload as a whole, reducing the problem for downstream algorithms. Postgres MCP Pro performs a limited form of workload compression by normalizing queries so that those generated from the same template appear as one. It weights each query equally, a simplification that works when the benefits to indexing are large.
Generate candidate indexes Once we have a list of SQL queries that we want to improve through indexing, we generate a list of indexes that we might want to add. To do this, we parse the SQL and identify any columns used in filters, joins, grouping, or sorting.
To generate all possible indexes we need to consider combinations of these columns, because Postgres supports multicolumn indexes. In the present implementation, we include only one permutation of each possible multicolumn index, which is selected at random. We make this simplification to reduce the search space because permutations often have equivalent performance. However, we hope to improve in this area.
Search for the optimal index configuration.
Our objective is to find the combination of indexes that optimally balances the performance benefits against the costs of storing and maintaining those indexes.
We estimate the performance improvement by using the "what if?" capabilities provided by the hypopg extension.
This simulates how the Postgres query optimizer will execute a query after the addition of indexes, and reports changes based on the actual Postgres cost model.
One challenge is that generating query plans generally requires knowledge of the specific parameter values used in the query. Query normalization, which is necessary to reduce the queries under consideration, removes parameter constants. Parameter values provided via bind variables are similarly not available to us.
To address this problem, we produce realistic constants that we can provide as parameters by sampling from the table statistics.
In version 16, Postgres added generic explain plan functionality, but it has limitations, for example around LIKE clauses, which our implementation does not have.
Search strategy is critical because evaluating all possible index combinations feasible only in simple situations. This is what most sets apart various indexing approaches. Adapting the approach of Microsoft's Anytime algorithm, we employ a greedy search strategy, i.e., find the best one-index solution, then find the best index to add to that to produce a two-index solution. Our search terminates when the time budget is exhausted or when a round of exploration fails to produce any gains above the minimum improvement threshold of 10%.
Cost-benefit analysis. When posed with two indexing alternatives, one which produces better performance and one which requires more space, how do we decide which to choose? Traditionally, index advisors ask for a storage budget and optimize performance with respect to that storage budget. We also take a storage budget, but perform a cost-benefit analysis throughout the optimization.
We frame this as the problem of selecting a point along the Pareto front—the set of choices for which improving one quality metric necessarily worsens another. In an ideal world, we might want to assess the cost of the storage and the benefit of improved performance in monetary terms. However, there is a simpler and more practical approach: to look at the changes in relative terms. Most people would agree that a 100x performance improvement is worth it, even if the storage cost is 2x. In our implementation, we use a configurable parameter to set this threshold. By default, we require the change in the log (base 10) of the performance improvement to be 2x the difference in the log of the space cost. This works out to allowing a maximum 10x increase in space for a 100x performance improvement.
Our implementation is most closely related to the Anytime Algorithm found in Microsoft SQL Server. Compared to Dexter, an automatic indexing tool for Postgres, we search a larger space and use different heuristics. This allows us to generate better solutions at the cost of longer runtime.
We also show the work done in each round of the search, including a comparison of the query plans before and after the addition of each index. This give the LLM additional context that it can use when responding to the indexing recommendations.
Postgres MCP Pro includes an experimental index tuning feature based on Optimization by LLM.
Instead of using heuristics to explore possible index configurations, we provide the database schema and query plans to an LLM and ask it to propose index configurations.
We then use hypopg to predict performance with the proposed indexes, then feed those results back into the LLM to produce a new set of suggestions.
We repeat this process until multiple rounds of iteration produce no further improvements.
Index optimization by LLM is has advantages when the index search space is large, or when indexes with many columns need to be considered.
Like traditional search-based approaches, it relies on the accuracy of the hypopg performance predictions.
In order to perform index optimization by LLM, you must provide an OpenAI API key by setting the OPENAI_API_KEY environment variable.
Database health checks identify tuning opportunities and maintenance needs before they lead to critical issues. In the present release, Postgres MCP Pro adapts the database health checks directly from PgHero. We are working to fully validate these checks and may extend them in the future.
Postgres MCP Pro uses psycopg3 to connect to Postgres using asynchronous I/O. Under the hood, psycopg3 uses the libpq library to connect to Postgres, providing access to the full Postgres feature set and an underlying implementation fully supported by the Postgres community.
Some other Python-based MCP servers use asyncpg, which may simplify installation by eliminating the libpq dependency.
Asyncpg is also probably faster than psycopg3, but we have not validated this ourselves.
Older benchmarks report a larger performance gap, suggesting that the newer psycopg3 has closed the gap as it matures.
Balancing these considerations, we selected psycopg3 over asyncpg.
We remain open to revising this decision in the future.
Like the Reference PostgreSQL MCP Server, Postgres MCP Pro takes Postgres connection information at startup. This is convenient for users who always connect to the same database but can be cumbersome when users switch databases.
An alternative approach, taken by PG-MCP, is provide connection details via MCP tool calls at the time of use. This is more convenient for users who switch databases, and allows a single MCP server to simultaneously support multiple end-users.
There must be a better approach than either of these. Both have security weaknesses—few MCP clients store the MCP server configuration securely (an exception is Goose), and credentials provided via MCP tools are passed through the LLM and stored in the chat history. Both also have usability issues in some scenarios.
The purpose of the schema information tool is to provide the calling AI agent with the information it needs to generate correct and performant SQL. For example, suppose a user asks, "How many flights took off from San Francisco and landed in Paris during the past year?" The AI agent needs to find the table that stores the flights, the columns that store the origin and destinations, and perhaps a table that maps between airport codes and airport locations.
Why provide schema information tools when LLMs are generally capable of generating the SQL to retrieve this information from Postgres directly?
Our experience using Claude indicates that the calling LLM is very good at generating SQL to explore the Postgres schema by querying the Postgres system catalog and the information schema (an ANSI-standardized database metadata view). However, we do not know whether other LLMs do so as reliably and capably.
Would it be better to provide schema information using MCP resources rather than MCP tools?
The Reference PostgreSQL MCP Server uses resources to expose schema information rather than tools. Navigating resources is similar to navigating a file system, so this approach is natural in many ways. However, resource support is less widespread than tool support in the MCP client ecosystem (see example clients). In addition, while the MCP standard says that resources can be accessed by either AI agents or end-user humans, some clients only support human navigation of the resource tree.
AI amplifies longstanding challenges of protecting databases from a range of threats, ranging from simple mistakes to sophisticated attacks by malicious actors. Whether the threat is accidental or malicious, a similar security framework applies, with aims that fall into three categories: confidentiality, integrity, and availability. The familiar tension between convenience and safety is also evident and pronounced.
Postgres MCP Pro's protected SQL execution mode focuses on integrity. In the context of MCP, we are most concerned with LLM-generated SQL causing damage—for example, unintended data modification or deletion, or other changes that might circumvent an organization's change management process.
The simplest way to provide integrity is to ensure that all SQL executed against the database is read-only. One way to do this is by creating a database user with read-only access permissions. While this is a good approach, many find this cumbersome in practice. Postgres does not provide a way to place a connection or session into read-only mode, so Postgres MCP Pro uses a more complex approach to ensure read-only SQL execution on top of a read-write connection.
Postgres MCP Provides a read-only transaction mode that prevents data and schema modifications. Like the Reference PostgreSQL MCP Server, we use read-only transactions to provide protected SQL execution.
To make this mechanism robust, we need to ensure that the SQL does not somehow circumvent the read-only transaction mode, say by issuing a COMMIT or ROLLBACK statement and then beginning a new transaction.
For example, the LLM can circumvent the read-only transaction mode by issuing a ROLLBACK statement and then beginning a new transaction.
For example:
ROLLBACK; DROP TABLE users;
To prevent cases like this, we parse the