1. MooseStack
  3. Table Engines
  5. MergeTree

MergeTree

MergeTree is the default engine for OlapTable and the most commonly used ClickHouse table engine. It's optimized for high-volume inserts and fast analytical queries on append-only data.

import { OlapTable, ClickHouseEngines } from "@514labs/moose-lib"; interface Event {  id: string;  timestamp: Date;  user_id: string;  action: string;  properties: Record<string, any>;} // MergeTree is the default—no engine parameter neededconst events = new OlapTable<Event>("events", {  orderByFields: ["timestamp", "user_id", "id"]}); // Or explicitly specifyconst explicitEvents = new OlapTable<Event>("events", {  engine: ClickHouseEngines.MergeTree,  orderByFields: ["timestamp", "user_id", "id"]});

Configuration Options

OptionDescription
orderByFieldsColumns for sorting and primary index (critical for query performance)
partitionByPartition expression (e.g., toYYYYMM(timestamp))
settingsEngine-specific settings as key-value pairs
ORDER BY matters

The orderByFields determines both the sort order and the primary index. Place your most common filter columns first for best query performance.

See Also

  • ReplacingMergeTree — When you need deduplication
  • OlapTable Reference — Full table configuration reference
  • ClickHouse MergeTree Engine — ClickHouse official documentation

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import { OlapTable, ClickHouseEngines } from "@514labs/moose-lib"; interface Event {  id: string;  timestamp: Date;  user_id: string;  action: string;  properties: Record<string, any>;} // MergeTree is the default—no engine parameter neededconst events = new OlapTable<Event>("events", {  orderByFields: ["timestamp", "user_id", "id"]}); // Or explicitly specifyconst explicitEvents = new OlapTable<Event>("events", {  engine: ClickHouseEngines.MergeTree,  orderByFields: ["timestamp", "user_id", "id"]});