Recern
Download
Recern Workspace · Documentation

Views

Recern samples each open connection every 5 seconds and keeps the last hour in memory, so charts have history from the moment you connect. Views refresh on their own; see Shortcuts and settings to change how often.

Slow view requests do not start overlapping polls. Responses from a previous view or connection are discarded when you navigate elsewhere.

Findings

Recern turns each server's statistics into findings, rated critical, warning or info: a session blocked by another, a long open transaction, an unused or duplicate index, a Redis server with no memory limit, a vector collection full of deleted records. Each finding explains itself and links to the view that shows the details.

PostgreSQL

  • Overview: transactions per second, connections against max_connections, cache hits, blocked sessions, activity charts and findings.
  • Sessions: client sessions by state, what each one is running, how long its transaction has been open, and whom it blocks.
  • Locks: wait chains (the blocked statement and the session holding its lock) and every lock held, with transaction id locks hidden by default.
  • Queries (with pg_stat_statements): statements ranked by total time, mean time, calls, rows, disk reads or temporary files.
  • Tables: size with indexes and TOAST, dead rows, sequential scans, writes, and when each table was last vacuumed and analyzed.
  • Indexes: unused, duplicate and redundant indexes with the space they take, and foreign keys without an index.

  • Console: see Safe Mode and the console and query history and export.

  • Vectors (with pgvector): vector columns, HNSW and IVFFlat indexes, distance operators and index parameters, search settings, index builds and vector-query statistics when available. Findings include large vector columns without an index. This view inspects indexes and usage; recall measurement is available for Recern Vector files.

MySQL

  • Overview: throughput, connections, buffer pool activity, uptime and findings.
  • Sessions: running and idle sessions, statements and transaction activity.
  • Locks: waiting transactions and blockers, when the server exposes the required diagnostics.
  • Queries: statement digests from Performance Schema, ranked by their cost.
  • Tables and Indexes: schema, storage, index usage and redundancy findings.
  • InnoDB: buffer pool, transaction, I/O and engine status.
  • Replication: replica status and lag when available.
  • Console: SQL with cancellation, Safe Mode, history, saved queries and CSV/JSON export.

A view explains when its diagnostic data is unavailable because of server capabilities or permissions.

Microsoft SQL Server

Overview shows client-measured probe latency and available diagnostics. Sessions, Locks and Queries use account-visible session and query-cache statistics; the cache is not a complete query history. Tables, Columns and Indexes show visible schema metadata and estimated row counts. Access & limits reports visible write/admin grants or marks permissions unverified. A restricted login may see only its own session. The Console is always read-only. See Microsoft SQL Server.

MongoDB

Overview, Collections, Documents, Indexes, Operations and a read-only JSON Console. Documents are paged in groups of 50; storage statistics have a bounded refresh budget and missing monitoring permissions are explained. See MongoDB.

ClickHouse

Overview, running Queries, Tables, skipping Indexes, Parts, Merges, Mutations, Replicas and a read-only SQL Console. Diagnostic views depend on readable system tables. See ClickHouse.

Cassandra

Overview, reported Topology, Keyspaces, Tables, Columns, secondary Indexes, partition Estimates and a read-only CQL Console. Local Compactions metadata appears when permitted. The chart measures CQL round-trip latency; it is not a cluster health check or a JMX metric. See Cassandra.

Qdrant

Overview, Collections, dense/sparse Vectors, Payload indexes, paginated Points, Cluster when permitted and a read-only JSON Console. Points display 100 per page. Overview labels partial catalog totals; the chart measures request latency. Counts are server metadata and do not measure recall. See Qdrant.

OpenSearch

Cluster Overview, Indices, Nodes, Shards, Mappings, manual Documents pages, Access & limits and a read-only JSON Search console. The chart measures root-endpoint request latency. Permission failures remain visible; account privileges are reported separately from Safe Mode. There are no search/indexing throughput charts or k-NN diagnostics in 0.5.0. See OpenSearch.

Redis, Valkey and Dragonfly

  • Overview: operations per second, memory, hit ratio, clients and findings.
  • Memory: where memory goes (data, key overhead, scripts, client buffers), peak, fragmentation and used memory over the last hour.
  • Clients: connections by client name, library or address; idle, blocked and pub/sub clients.
  • Slow log: logged commands on a timeline against the threshold, and total time by command.
  • Keys: keys matching a pattern, read page by page with SCAN, with their type, time to live and approximate memory.

  • Console: see Safe Mode and the console and query history and export.

  • Vectors (when supported): search indexes and their vector fields, vector memory, indexing failures and their reasons; Redis 8 vector sets when the server provides them. Availability depends on the actual server and installed modules.

SQLite

  • Overview: database size, pages, free space, journal mode, WAL size and findings.
  • Tables: tables, columns, storage and unused space.
  • Indexes: indexed columns, redundant indexes and foreign keys without a supporting index.
  • Pragmas: database settings and an integrity check.
  • Console: SQL with cancellation, Safe Mode, history, saved queries and CSV/JSON export.

Recern Vector

  • Overview: vectors, file size, memory, deleted records, collections, f32/int8 precision, file format version and findings. Committed changes in the WAL are included.
  • Index: for each collection, nodes per HNSW layer, links per node against what m allows, unreachable records and memory.
  • Recall: approximate search compared with exact search at several values of ef, with latency, so you can see what raising ef_search buys and costs.