DQL pipe operators

Every operator in the pipe catalog, generated from the catalog the engine registers, so it cannot describe an operator that does not ship.

A pipe is an ordered chain of these operators applied to a stream of rows. They appear below in catalog order, which follows the shape of a typical pipe: source, filter, transform, aggregate, sort, side effect.

Column key01

Column	Meaning
Live-safe	Pure and deterministic with default config, so it can run on a live-updating result set.
Pushable	Can fold into the SQL prefix. The planner makes the final call from the field types.
Requires	Host services the operator needs in its `OpContext`. Blank means it works anywhere.

Index02

Operator	Summary	Live-safe	Pushable	Requires
`filter`	Keep rows that match a predicate	✅	✅	`eval`
`project`	Select / alias columns	✅	✅
`rename`	Rename columns	✅	✅
`drop`	Remove columns	✅	—
`compute`	Add a computed column	✅	—	`eval`, `formula`
`transform`	Compute multiple columns in one stage	✅	—	`eval`
`cast`	Convert column types	✅	—
`dropNulls`	Drop rows with nulls in named columns	✅	✅
`fillNulls`	Replace nulls in named columns	✅	—
`flatten`	Unnest an array column	✅	—
`unnestObject`	Spread an object column into root keys	✅	—
`nest`	Group rows into nested arrays	✅	—
`pivot`	Rows → columns	✅	—
`unpivot`	Columns → rows	✅	—
`distinct`	Deduplicate rows	✅	—
`dedupe`	Keep one row per identity key	✅	—
`sample`	Random subset of rows	✅	—
`assert`	Fail the query when an expression is false	✅	—	`eval`
`timeBucket`	Bucket rows into fixed time intervals	✅	—
`gapfill`	Fill missing time intervals	✅	—
`sort`	Order rows	✅	✅
`limit`	Cap row count	✅	✅
`skip`	Drop the first N rows	✅	✅
`topPerGroup`	Top N rows per partition	✅	—
`groupBy`	Set keys for the next aggregate	✅	✅
`aggregate`	Fold rows into groups	✅	✅
`histogram`	Bucket numeric values into equal-width bins	✅	—
`window`	Per-row computation within a partition	✅	—
`lookup`	Hash-join with another dataset	✅	—	`classic`
`asofJoin`	Join on the closest timestamp	✅	—	`classic`
`crossJoin`	Cartesian product with another dataset	✅	—	`classic`
`intersect`	Rows present in every source	✅	—	`classic`
`except`	Rows in left but not in right	✅	—	`classic`
`callFunction`	Invoke a registered DTL function	—	—	`functionRegistry`
`callApp`	Invoke a managed app	—	—	`appCaller`
`algo`	Run a registered algorithm	—	—	`algorithms`
`branch`	Per-row conditional sub-pipes	✅	—	`eval`
`merge`	Fan-out then concat	✅	—
`tap`	Pass-through with a debug label	✅	—

`filter`03

Keep rows that match a predicate

Live-safe by default: yes Pushable: yes Requires: eval

Filters rows by a WHERE clause. Plain field/op/value forms push down to SQL; DTL expr forms run in-memory.

Field	Type	Required	Description
`where`	any	yes	Conditions a row must satisfy to be kept. Use simple `{field, op, value}` shape for SQL-pushable filters, or `{expr: "…"}` for DTL expressions evaluated in-memory.

Plain comparison

{
  "op": "filter",
  "where": {
    "field": "level",
    "op": "==",
    "value": "ERROR"
  }
}

DTL expression

{
  "op": "filter",
  "where": {
    "expr": "ts > now() - duration(\"1h\")"
  }
}

`project`04

Select / alias columns

Live-safe by default: yes Pushable: yes

Reduces each row to a chosen subset of columns, optionally renaming them.

Field	Type	Required	Description
`select`	array		Columns to keep, in order. Each entry is `{field, as?}` — set `as` to rename.
`drop`	array of string		Alternative to `select` — instead of listing what to keep, list what to remove. Mutually exclusive with `select`.

Pick fields

{
  "op": "project",
  "select": [
    {
      "field": "id"
    },
    {
      "field": "name"
    }
  ]
}

`rename`05

Rename columns

Live-safe by default: yes Pushable: yes

Rewrites column keys in-place. The map is from -> to.

Field	Type	Required	Description
`map`	object	yes	Object whose keys are the existing column names and whose values are the new names. Pairs not listed are left untouched. (input: column-rename-map)

id → key

{
  "map": {
    "id": "key"
  },
  "op": "rename"
}

`drop`06

Remove columns

Live-safe by default: yes Pushable: no

Deletes the named columns from each row.

Field	Type	Required	Description
`columns`	array of string	yes	Names of columns to remove from every row.

Drop secrets

{
  "columns": [
    "password",
    "secret"
  ],
  "op": "drop"
}

`compute`07

Add a computed column

Live-safe by default: yes Pushable: no Requires: eval, formula

Evaluates a DTL expression (kind:"expr") or Excel-style formula (kind:"formula") per row and stores the result under as.

Field	Type	Required	Description
`as`	string	yes	Column to write the computed value into. Overwrites any existing column with the same name. (input: column-output)
`kind`	string		Which language `expr` / `formula` is in. Defaults to DTL `expr`. Default: `expr`.
`expr`	string	conditional {"kind":["expr",""]}	DTL expression evaluated against each row. Used when `kind` is `expr`. (input: dtl-expression)
`formula`	string	conditional {"kind":["formula"]}	Spreadsheet formula evaluated against each row. Used when `kind` is `formula`. (input: formula)

DTL expr

{
  "as": "doubled",
  "expr": "value * 2",
  "op": "compute"
}

Formula

{
  "as": "tax",
  "formula": "price * 0.1",
  "kind": "formula",
  "op": "compute"
}

`transform`08

Compute multiple columns in one stage

Live-safe by default: yes Pushable: no Requires: eval

Like compute but takes a list. Entries evaluate in order and can reference earlier results. Use from for plain column copies and replace: true to drop everything not produced.

Field	Type	Required	Description
`compute`	array of object	yes	Ordered list of column definitions. Each entry uses `expr` (DTL) or `from` (column copy).
`drop`	array of string		Optional. Columns to remove from the output after computation.
`replace`	boolean		When true, drop every column not produced by `compute`. Useful for reshape-and-rename in one step. Default: `false`.

Add several columns

{
  "compute": [
    {
      "as": "total",
      "expr": "a + b"
    },
    {
      "as": "ratio",
      "expr": "a / b"
    }
  ],
  "op": "transform"
}

Reshape

{
  "compute": [
    {
      "as": "id",
      "from": "_id"
    },
    {
      "as": "score",
      "expr": "wins / matches"
    }
  ],
  "op": "transform",
  "replace": true
}

`cast`09

Convert column types

Live-safe by default: yes Pushable: no

Coerce columns to int / float / bool / string / timestamp. onError chooses null (default) | skip | fail.

Field	Type	Required	Description
`casts`	array of object	yes	List of `{field, to, onError?}` rules applied in order.

`dropNulls`10

Drop rows with nulls in named columns

Live-safe by default: yes Pushable: yes

When any is true (default) drops rows where ANY listed column is null; when false drops only when EVERY listed column is null.

Field	Type	Required	Description
`columns`	array of string		Columns inspected for null. Empty means every column on each row.
`any`	boolean		When true, drop a row if ANY listed column is null. When false, drop only when EVERY listed column is null. Default: `true`.

`fillNulls`11

Replace nulls in named columns

Live-safe by default: yes Pushable: no

Methods: zero, value, lastValue, nextValue, mean. lastValue/nextValue require partitionBy + orderBy for deterministic forward/backward fill.

Field	Type	Required	Description
`method`	string		`value` uses the literal `value`; `zero` uses 0; `lastValue` carries the previous non-null forward; `nextValue` carries the next non-null backward; `mean` uses the column mean. Default: `value`.
`value`	any	conditional {"method":["value"]}	Used when `method` is `value`. Any JSON scalar.
`columns`	array of string		Columns whose null cells are replaced. Empty means every column on each row.
`partitionBy`	array of string	conditional {"method":["lastValue","nextValue"]}	Required for `lastValue` / `nextValue`. Within each partition, ordering and carry semantics apply independently.
`orderBy`	array	conditional {"method":["lastValue","nextValue"]}	Required for `lastValue` / `nextValue` to define what "previous" / "next" means within a partition.

`flatten`12

Unnest an array column

Live-safe by default: yes Pushable: no

Emits one row per array element. When as is set, the element is stored under that key and the original field is preserved.

Field	Type	Required	Description
`field`	string	yes	Column whose array values are exploded into separate rows. (input: column)
`as`	string		Optional. Column name to store each element under. When unset, the element replaces the array column on each row. (input: column-output)
`indexAs`	string		Optional. Column name to store the element's 0-based index in the source array. (input: column-output)
`preserveEmpty`	boolean		When true, rows whose array is empty or null still produce one output row (with the element column nil). Default drops them. Default: `false`.

Unnest tags

{
  "field": "tags",
  "op": "flatten"
}

`unnestObject`13

Spread an object column into root keys

Live-safe by default: yes Pushable: no

Useful for JSONB/metadata blobs whose nested keys you want as top-level columns.

Field	Type	Required	Description
`field`	string	yes	Column whose object value's keys are spread onto the root row. (input: column)
`prefix`	string		Optional. Prepended to every spread key (e.g. `m_` produces `m_owner`). (input: prefix)
`drop`	boolean		When true, the original object column is removed after spreading. Default: `false`.

`nest`14

Group rows into nested arrays

Live-safe by default: yes Pushable: no

Inverse of flatten: emits one row per group with the remaining columns collected into an array under into.

Field	Type	Required	Description
`by`	array of string	yes	Partition keys; one output row is emitted per unique combination.
`into`	string	yes	Name of the output column where the per-group array of nested records is stored. (input: column-output)
`include`	array of string		Optional. Columns to include in each nested record. Defaults to every column not in `by`.

`pivot`15

Rows → columns

Live-safe by default: yes Pushable: no

Each unique value in columnKey becomes a column. aggregate controls how to combine duplicates (sum/avg/count/min/max/first/last).

Field	Type	Required	Description
`rowKeys`	array of string		Columns whose distinct combinations identify each output row.
`columnKey`	string	yes	Column whose distinct values become the names of new columns. (input: column)
`valueField`	string	yes	Column whose values populate the cells. (input: column)
`aggregate`	string		How to combine multiple input rows that map to the same cell. Default: `first`.
`fillValue`	any		Value to use for output cells with no source row. Defaults to null.
`prefix`	string		Optional string prepended to every generated column name. (input: prefix)

`unpivot`16

Columns → rows

Live-safe by default: yes Pushable: no

Melts named columns into name/value pairs (one output row per input row × valueCol).

Field	Type	Required	Description
`idCols`	array of string		Columns kept verbatim on every output row. Empty means every column not in `valueCols`.
`valueCols`	array of string		Columns whose values are unstacked into rows. Empty means every column not in `idCols`.
`nameAs`	string	yes	Output column that records the source column name. (input: column-output)
`valueAs`	string	yes	Output column that records the cell value. (input: column-output)

`distinct`17

Deduplicate rows

Live-safe by default: yes Pushable: no

When by is empty, uniqueness uses every column; otherwise only the named keys.

Field	Type	Required	Description
`by`	array of string		Columns whose combined values define a row's identity. Leave empty to deduplicate using every column.

`dedupe`18

Keep one row per identity key

Live-safe by default: yes Pushable: no

Different from distinct (full-row equality): pick first or last row per key, with optional ordering.

Field	Type	Required	Description
`by`	array of string	yes	Columns whose combined values define a row's identity.
`keep`	string		Whether to keep the first row encountered per identity (`first`) or the last (`last`). Combined with `orderBy` for deterministic results. Default: `first`.
`orderBy`	array		Optional. Sort applied within each identity group before applying `keep`.

`sample`19

Random subset of rows

Live-safe by default: yes Pushable: no

Either n (target size) or ratio (0..1). seed makes output deterministic. Method: random (reservoir) | systematic (every k-th).

Field	Type	Required	Description
`method`	string		`random` uses reservoir sampling; `systematic` keeps every k-th row. Default: `random`.
`n`	integer		Sample size in rows. Mutually exclusive with `ratio`.
`ratio`	number		Fraction of input rows to keep, between 0 and 1. Mutually exclusive with `n`.
`seed`	integer		Optional integer seed for deterministic sampling. Same seed + same input ⇒ same output.

`assert`20

Fail the query when an expression is false

Live-safe by default: yes Pushable: no Requires: eval

Runtime guardrail. scope=row evaluates per row; scope=overall checks once with count available.

Field	Type	Required	Description
`scope`	string		`row` evaluates the expression per row; `overall` evaluates once at the end with the row `count` available. Default: `row`.
`expr`	string	yes	DTL expression that must be truthy. Falsy results fail the query. (input: dtl-expression)
`message`	string		Custom error message returned when the assertion fails.

`timeBucket`21

Bucket rows into fixed time intervals

Live-safe by default: yes Pushable: no

Adds a column with the start of the bucket containing each row's timestamp. Pair with groupBy + aggregate for time-series rollups.

Field	Type	Required	Description
`field`	string	yes	Column carrying the row's timestamp. (input: column)
`interval`	string	yes	Duration string for the bucket width — `"5m"`, `"1h"`, `"1d"`. (input: duration)
`as`	string	yes	Column to write the bucket-start timestamp into. (input: column-output)
`tz`	string		Optional IANA timezone (e.g. `America/New_York`) used to align bucket boundaries. Defaults to UTC. (input: timezone)
`origin`	string		Optional RFC3339 anchor that defines where buckets start. Defaults to the Unix epoch. (input: timestamp)

5-minute buckets

{
  "as": "bucket",
  "field": "ts",
  "interval": "5m",
  "op": "timeBucket"
}

`gapfill`22

Fill missing time intervals

Live-safe by default: yes Pushable: no

Emits synthetic rows for time buckets missing from the input. Useful before charting sparse sensor streams.

Field	Type	Required	Description
`field`	string	yes	Column carrying the row's timestamp. (input: column)
`interval`	string	yes	Duration string (`"5m"`, `"1h"`) describing the gap between expected timestamps. (input: duration)
`method`	string		How to populate value columns on synthetic rows: `zero`, `null`, `lastValue` (carry forward), or `value` (use the literal `value` field). Default: `null`.
`value`	any	conditional {"method":["value"]}	Used when `method` is `value`. Any JSON scalar.
`from`	string		Optional RFC3339 lower bound. Defaults to the earliest timestamp in the input. (input: timestamp)
`to`	string		Optional RFC3339 upper bound. Defaults to the latest timestamp in the input. (input: timestamp)
`groupBy`	array of string		Optional. Treat the input as multiple independent time series, gapfilling each partition separately.
`carry`	array of string	conditional {"method":["lastValue"]}	Columns whose value is copied from the most recent real row when `method` is `lastValue`.

`sort`23

Order rows

Live-safe by default: yes Pushable: yes

Sorts by one or more keys. Direction defaults to asc.

Field	Type	Required	Description
`by`	array	yes	Ordered list of `{field, dir}` keys. Earlier entries are the primary sort; later entries break ties.

Top 10 by ts

{
  "by": [
    {
      "dir": "desc",
      "field": "ts"
    }
  ],
  "op": "sort"
}

`limit`24

Cap row count

Live-safe by default: yes Pushable: yes

Field	Type	Required	Description
`n`	integer	yes	Keep at most this many rows. Set to 0 to drop everything.

`skip`25

Drop the first N rows

Live-safe by default: yes Pushable: yes

Field	Type	Required	Description
`n`	integer	yes	Number of rows to discard from the start of the input. Combined with limit gives offset/page semantics.

`topPerGroup`26

Top N rows per partition

Live-safe by default: yes Pushable: no

Keeps the highest- (or lowest-) ranked N rows per group. With no partition, equivalent to top N overall.

Field	Type	Required	Description
`n`	integer	yes	How many rows to keep per partition (1 = top-1).
`partitionBy`	array of string		Optional. Columns that split the input into partitions. Empty = single partition (top-N overall).
`by`	array	yes	Sort keys used to rank rows within each partition. The first key is primary; later keys break ties.

`groupBy`27

Set keys for the next aggregate

Live-safe by default: yes Pushable: yes

On its own this is a pass-through. The planner pairs it with the immediately-following aggregate op.

Field	Type	Required	Description
`keys`	array of string	yes	Columns whose unique combinations define each group. The downstream aggregate folds rows within each combination.

`aggregate`28

Fold rows into groups

Live-safe by default: yes Pushable: yes

Computes COUNT, SUM, AVG, MIN, MAX over groups defined by a preceding groupBy (or the whole stream when standalone).

Field	Type	Required	Description
`keys`	array of string		Optional. Same shape as `groupBy.keys` — when set, the aggregate uses these keys directly without a preceding `groupBy` stage.
`aggs`	array	yes	Ordered list of `{fn, field, as}` clauses (e.g. `{fn: "SUM", field: "amount", as: "total"}`).

`histogram`29

Bucket numeric values into equal-width bins

Live-safe by default: yes Pushable: no

Replaces input rows with one row per bin: {binStart, binEnd, count}. Provide explicit min/max or let the op derive them.

Field	Type	Required	Description
`field`	string	yes	Column whose numeric values are bucketed. (input: column)
`bins`	integer	yes	Number of equal-width bins to produce.
`min`	number		Optional lower bound. Defaults to the minimum value seen in the input.
`max`	number		Optional upper bound. Defaults to the maximum value seen in the input.
`asCount`	string		Output column for the per-bin count. (input: column-output) Default: `count`.
`asStart`	string		Output column for each bin's lower edge. (input: column-output) Default: `binStart`.
`asEnd`	string		Output column for each bin's upper edge. (input: column-output) Default: `binEnd`.

`window`30

Per-row computation within a partition

Live-safe by default: yes Pushable: no

row_number, rank, dense_rank, lag, lead, first_value, last_value. Output preserves input row order.

Field	Type	Required	Description
`fn`	string	yes	Which windowing function to compute per row.
`partitionBy`	array of string		Columns that split the input into independent windows. Within each partition, the function is computed in `orderBy` order.
`orderBy`	array		Sort keys applied within each partition before the function runs. Required for ranking/lag/lead semantics.
`field`	string	conditional {"fn":["lag","lead","first_value","last_value"]}	Column the window function reads. Required for `lag`/`lead`/`first_value`/`last_value`; ignored for ranking functions. (input: column)
`offset`	integer		Row offset for `lag`/`lead`. Defaults to 1 row.
`default`	any		Value to emit when the window function falls outside the partition (e.g. `lag(1)` on the first row).
`as`	string	yes	Column to write the window value into. (input: column-output)

`lookup`31

Hash-join with another dataset

Live-safe by default: yes Pushable: no Requires: classic

Fetches the right side via a secondary classic query. Use cacheTtlMs to avoid re-fetching on every live update.

Field	Type	Required	Description
`dataset`	string	yes	Dataset name to fetch the join's right side from. (input: dataset)
`on`	object	yes	Column names on each side that must equal for a match.
`mode`	string		`left` keeps every left row; `inner` drops left rows with no match. Default: `left`.
`as`	string		Optional. When set, the matched right-side row is nested under this column instead of being flattened into the left row. (input: column-output)
`select`	array of string		Optional. Subset of right-side columns to merge in. Empty means all columns.
`where`	any		Optional WHERE clause applied to the right-side dataset before the join.
`limit`	integer		Optional. Cap the number of right-side rows fetched (useful when `dataset` is large).
`cacheTtlMs`	integer		Cache the right-side fetch for this many milliseconds. 0 disables caching. Useful when the same lookup runs many times under live mode. Default: `0`.

`asofJoin`32

Join on the closest timestamp

Live-safe by default: yes Pushable: no Requires: classic

For each left row, finds the right row with the closest timestamp on a matching key. Direction backward (default) | forward | nearest, with optional tolerance.

Field	Type	Required	Description
`dataset`	string	yes	Dataset to fetch the right side from. (input: dataset)
`leftTime`	string	yes	Column on the streaming (left) side carrying the row's timestamp. (input: column)
`rightTime`	string	yes	Column on the looked-up (right) side carrying the row's timestamp. (input: dataset-column)
`leftKey`	string		Optional. Column on the left whose value must equal `rightKey` for a match. (input: column)
`rightKey`	string		Optional. Column on the right whose value must equal `leftKey` for a match. (input: dataset-column)
`direction`	string		`backward` finds the latest right row at or before the left row; `forward` the earliest at or after; `nearest` the absolute closest. Default: `backward`.
`tolerance`	string		Optional duration (`"1m"`, `"30s"`). Drops matches further than this from the left row's timestamp. (input: duration)
`as`	string		Optional. When set, the matched right row is nested under this column. (input: column-output)
`select`	array of string		Optional subset of right-side columns to merge in. Empty means all columns.
`where`	any		Optional WHERE clause applied to the right-side dataset before the join.
`limit`	integer		Optional cap on right-side rows fetched.

`crossJoin`33

Cartesian product with another dataset

Live-safe by default: yes Pushable: no Requires: classic

Output size is N × M — use sparingly. Right-side rows can be filtered with where and capped with limit.

Field	Type	Required	Description
`dataset`	string	yes	Dataset to fetch the cartesian-product right side from. (input: dataset)
`as`	string		Optional. When set, each right row is nested under this column instead of being flattened into the left row. (input: column-output)
`select`	array of string		Optional subset of right-side columns to merge in. Empty means all columns.
`where`	any		Optional WHERE clause applied to the right-side dataset before the cross-join.
`limit`	integer		Optional cap on right-side rows. Strongly recommended to bound output size.

`intersect`34

Rows present in every source

Live-safe by default: yes Pushable: no Requires: classic

Set intersection across N sub-pipes, identified by by keys (or full-row equality).

Field	Type	Required	Description
`sources`	array of object	yes	Two or more sub-pipes. Output rows are those present in every sub-pipe (under the chosen identity).
`by`	array of string		Optional. When set, intersection compares only these columns. Empty falls back to full-row equality.

`except`35

Rows in left but not in right

Live-safe by default: yes Pushable: no Requires: classic

Field	Type	Required	Description
`left`	object	yes	Source whose rows are kept when not present in `right`.
`right`	object	yes	Source whose rows are subtracted from `left`.
`by`	array of string		Optional. When set, set difference compares only these columns. Empty falls back to full-row equality.

`callFunction`36

Invoke a registered DTL function

Live-safe by default: no Pushable: no Requires: functionRegistry

Calls a function from the function extension. pure: true declares the function side-effect-free and makes it live-safe.

Field	Type	Required	Description
`name`	string	yes	Fully qualified DTL function name (e.g. `geo::lookup`). (input: function-name)
`mode`	string		`perRow` calls the function once per row; `batch` passes the whole row stream to the function once. Default: `perRow`.
`pure`	boolean		When true, asserts the function has no side effects so live mode can re-run it on each update. Default: `false`.
`args`	object		Object passed to the function. Values may reference row columns via `$columnName`.
`literalArgs`	boolean		When true, `$column`-style refs in `args` are passed verbatim instead of resolved against the row.
`as`	string		Column to store the function result under. (input: column-output)

Per-row pure

{
  "args": {
    "x": "$value"
  },
  "name": "math::abs",
  "op": "callFunction",
  "pure": true
}

`callApp`37

Invoke a managed app

Live-safe by default: no Pushable: no Requires: appCaller

Calls an external app via the runtime extension. Always non-live-safe; live subscriptions require dryRun: true.

Field	Type	Required	Description
`appId`	string	yes	Identifier of the managed app to invoke. (input: app-id)
`method`	string		App method to call. Defaults to `transform`. Default: `transform`.
`capability`	string		Capability namespace the app must expose. Defaults to `pipe_query`. Default: `pipe_query`.
`batch`	boolean		When true, the entire row stream is sent to the app once. When false, the app is invoked per row. Default: `true`.
`payload`	object		Object merged into the app invocation payload alongside the rows.
`dataset`	string		Optional dataset name passed to the app for context. (input: dataset)

`algo`38

Run a registered algorithm

Live-safe by default: no Pushable: no Requires: algorithms

Invokes a native or external algorithm from the shared catalog (e.g. minmax_scale, kmeans, robust_zscore). params are forwarded verbatim to the algorithm — see its descriptor for accepted keys. Live-safety depends on the chosen algorithm: pure ones (most ETL transforms) are live-safe; external/stateful ones are not.

Field	Type	Required	Description
`name`	string	yes	Identifier of a registered algorithm (e.g. `minmax_scale`, `kmeans`). Must exist in the algorithm catalog or the stage fails at build time.
`params`	object		Algorithm-specific options passed through unchanged. Each algorithm documents its own keys in its catalog descriptor (e.g. `minmax_scale` takes `column` and `as`).

Min-max scale a column

{
  "name": "minmax_scale",
  "op": "algo",
  "params": {
    "as": "v_scaled",
    "column": "v"
  }
}

`branch`39

Per-row conditional sub-pipes

Live-safe by default: yes Pushable: no Requires: eval

Routes each row through then or else based on a DTL predicate. Live-safety propagates from the children.

Field	Type	Required	Description
`when`	string	yes	DTL expression evaluated per row. Truthy results take the `then` branch. (input: dtl-expression)
`then`	array	yes	Stages applied to rows where the predicate is truthy.
`else`	array		Optional. Stages applied to rows where the predicate is falsy. Empty drops the row.

`merge`40

Fan-out then concat

Live-safe by default: yes Pushable: no

Runs each sub-pipe against a clone of the input and concatenates outputs.

Field	Type	Required	Description
`sources`	array of object	yes	List of sub-pipes. Each receives a clone of the input rows; outputs are concatenated in order.

`tap`41

Pass-through with a debug label

Live-safe by default: yes Pushable: no

Records the row count against a label and returns rows unchanged.

Field	Type	Required	Description
`label`	string		Label that surfaces in `stats.pipe[].label` so this checkpoint is identifiable in the response.

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Query reference

Editor support

Operators

DQL pipe operators

Column key01

Index02

filter03

project04

rename05

drop06

compute07

transform08

cast09

dropNulls10

fillNulls11

flatten12

unnestObject13

nest14

pivot15

unpivot16

distinct17

dedupe18

sample19

assert20

timeBucket21

gapfill22

sort23

limit24

skip25

topPerGroup26

groupBy27

aggregate28

histogram29

window30

lookup31

asofJoin32

crossJoin33

intersect34

except35

callFunction36

callApp37

algo38

branch39

merge40

tap41

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`filter`03

`project`04

`rename`05

`drop`06

`compute`07

`transform`08

`cast`09

`dropNulls`10

`fillNulls`11

`flatten`12

`unnestObject`13

`nest`14

`pivot`15

`unpivot`16

`distinct`17

`dedupe`18

`sample`19

`assert`20

`timeBucket`21

`gapfill`22

`sort`23

`limit`24

`skip`25

`topPerGroup`26

`groupBy`27

`aggregate`28

`histogram`29

`window`30

`lookup`31

`asofJoin`32

`crossJoin`33

`intersect`34

`except`35

`callFunction`36

`callApp`37

`algo`38

`branch`39

`merge`40

`tap`41

Got something
hard to build?