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fix(mcp): reduce describe_source timeouts by using rollup tables for map key discovery #2426

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Merged
kodiakhq merged 4 commits into from
Jun 8, 2026
Merged

fix(mcp): reduce describe_source timeouts by using rollup tables for map key discovery #2426

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eb9eda4
fix(mcp): reduce describe_source timeouts by using rollup tables for …
brandon-pereira Jun 8, 2026
f6b20ff
chore: add changeset
brandon-pereira Jun 8, 2026
3a170e8
fix(mcp): pass abort signal to getMapKeys ClickHouse queries
brandon-pereira Jun 8, 2026
b4d6f7a
Merge branch 'main' into claude/fix-describe-source-timeout
kodiakhq[bot] Jun 8, 2026
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5 changes: 5 additions & 0 deletions .changeset/fix-describe-source-timeout.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"@hyperdx/api": patch
---

fix(mcp): reduce describe_source timeouts by using rollup tables for map key discovery
27 changes: 16 additions & 11 deletions packages/api/src/mcp/tools/sources/describeSource.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,19 @@ async function describeSourceSchema(
// Track which sampling stages were skipped due to timeout
const skippedStages: string[] = [];

// Shared by stages 2–4 so map-key discovery can use rollup tables
// instead of falling back to expensive main-table scans.
const metadataMVs =
'metadataMaterializedViews' in source
? source.metadataMaterializedViews
: undefined;

const now = new Date();
const dateRange: [Date, Date] = [
new Date(now.getTime() - VALUE_SAMPLE_LOOKBACK_MS),
now,
];

// ── 1. Column schema ──────────────────────────────────────────────────
const columns = await metadata.getColumns({
databaseName,
Expand Down Expand Up @@ -170,6 +183,9 @@ async function describeSourceSchema(
column: col.name,
maxKeys: 50,
connectionId,
metadataMVs,
dateRange,
signal,
});
mapKeysResults[col.name] = keys;
} catch (e) {
Expand Down Expand Up @@ -200,17 +216,6 @@ async function describeSourceSchema(

const lowCardinalityValues: Record<string, string[]> = {};

const metadataMVs =
'metadataMaterializedViews' in source
? source.metadataMaterializedViews
: undefined;

const now = new Date();
const dateRange: [Date, Date] = [
new Date(now.getTime() - VALUE_SAMPLE_LOOKBACK_MS),
now,
];

if (lcColumns.length > 0 && !signal.aborted) {
try {
const results = await metadata.getAllKeyValues({
Expand Down
9 changes: 9 additions & 0 deletions packages/common-utils/src/core/metadata.ts
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Expand Up @@ -351,6 +351,7 @@ export class Metadata {
metadataMVs,
dateRange,
timestampValueExpression,
signal,
}: {
databaseName: string;
tableName: string;
Expand All @@ -361,6 +362,7 @@ export class Metadata {
metadataMVs?: MetadataMaterializedViews;
dateRange?: [Date, Date];
timestampValueExpression?: string;
signal?: AbortSignal;
}) {
// Align date range to rollup granularity for consistent cache keys
const alignedDateRange =
Expand Down Expand Up @@ -419,6 +421,7 @@ export class Metadata {
max_execution_time: 15,
max_rows_to_read: '0',
},
abort_signal: signal,
})
.then(res => res.json<{ Key: string }>())
.then(d => d.data.map(row => row.Key).filter(k => k));
Expand Down Expand Up @@ -524,6 +527,7 @@ export class Metadata {
// Set the value to 0 (unlimited) so that the LIMIT is used instead
max_rows_to_read: '0',
},
abort_signal: signal,
})
.then(res => res.json<{ keysArr?: string[]; key?: string }>())
.then(d => {
Expand Down Expand Up @@ -640,6 +644,7 @@ export class Metadata {
connectionId,
dateRange,
timestampValueExpression,
signal,
}: {
databaseName: string;
tableName: string;
Expand All @@ -649,6 +654,7 @@ export class Metadata {
dateRange?: [Date, Date];
timestampValueExpression?: string;
connectionId: string;
signal?: AbortSignal;
}) {
const dateRangeCacheSuffix =
dateRange && timestampValueExpression
Expand Down Expand Up @@ -719,6 +725,7 @@ export class Metadata {
read_overflow_mode: 'break',
...this.getClickHouseSettings(),
},
abort_signal: signal,
})
.then(res => res.json<{ value: string }>())
.then(d => d.data.map(row => row.value));
Expand Down Expand Up @@ -1464,6 +1471,7 @@ export class Metadata {
connectionId,
dateRange,
timestampValueExpression,
signal,
});
return { key: p.keyExpression, value: fallback };
}),
Expand All @@ -1482,6 +1490,7 @@ export class Metadata {
connectionId,
dateRange,
timestampValueExpression,
signal,
});
return { key: p.keyExpression, value };
}),
Expand Down
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