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590 lines
10 KiB
Markdown
590 lines
10 KiB
Markdown
---
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slug: /en/sql-reference/functions/bitmap-functions
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sidebar_position: 25
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sidebar_label: Bitmap
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---
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# Bitmap Functions
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Bitmaps can be constructed in two ways. The first way is constructed by aggregation function groupBitmap with `-State`, the other way is to constructed a bitmap from an Array object.
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## bitmapBuild
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Builds a bitmap from an unsigned integer array.
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**Syntax**
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``` sql
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bitmapBuild(array)
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```
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**Arguments**
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- `array` – Unsigned integer array.
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**Example**
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``` sql
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SELECT bitmapBuild([1, 2, 3, 4, 5]) AS res, toTypeName(res);
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```
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``` text
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┌─res─┬─toTypeName(bitmapBuild([1, 2, 3, 4, 5]))─────┐
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│ │ AggregateFunction(groupBitmap, UInt8) │
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└─────┴──────────────────────────────────────────────┘
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```
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## bitmapToArray
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Converts bitmap to an integer array.
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**Syntax**
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``` sql
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bitmapToArray(bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapBuild([1, 2, 3, 4, 5])) AS res;
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```
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Result:
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``` text
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┌─res─────────┐
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│ [1,2,3,4,5] │
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└─────────────┘
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```
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## bitmapSubsetInRange
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Returns the subset of a bitmap with bits within a value interval.
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**Syntax**
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``` sql
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bitmapSubsetInRange(bitmap, range_start, range_end)
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```
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**Arguments**
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- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
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- `range_start` – Start of the range (inclusive). Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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- `range_end` – End of the range (exclusive). Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapSubsetInRange(bitmapBuild([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,100,200,500]), toUInt32(30), toUInt32(200))) AS res;
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```
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Result:
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``` text
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┌─res───────────────┐
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│ [30,31,32,33,100] │
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└───────────────────┘
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```
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## bitmapSubsetLimit
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Returns a subset of a bitmap with smallest bit value `range_start` and at most `cardinality_limit` elements.
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**Syntax**
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``` sql
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bitmapSubsetLimit(bitmap, range_start, cardinality_limit)
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```
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**Arguments**
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- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
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- `range_start` – Start of the range (inclusive). Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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- `cardinality_limit` – Maximum cardinality of the subset. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapSubsetLimit(bitmapBuild([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,100,200,500]), toUInt32(30), toUInt32(200))) AS res;
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```
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Result:
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``` text
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┌─res───────────────────────┐
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│ [30,31,32,33,100,200,500] │
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└───────────────────────────┘
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```
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## subBitmap
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Returns a subset of the bitmap, starting from position `offset`. The maximum cardinality of the returned bitmap is `cardinality_limit`.
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**Syntax**
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``` sql
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subBitmap(bitmap, offset, cardinality_limit)
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```
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**Arguments**
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- `bitmap` – The bitmap. Type: [Bitmap object](#bitmap_functions-bitmapbuild).
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- `offset` – The position of the first element of the subset. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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- `cardinality_limit` – The maximum number of elements in the subset. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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**Example**
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``` sql
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SELECT bitmapToArray(subBitmap(bitmapBuild([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,100,200,500]), toUInt32(10), toUInt32(10))) AS res;
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```
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Result:
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``` text
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┌─res─────────────────────────────┐
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│ [10,11,12,13,14,15,16,17,18,19] │
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└─────────────────────────────────┘
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```
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## bitmapContains
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Checks whether the bitmap contains an element.
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``` sql
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bitmapContains(bitmap, needle)
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```
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**Arguments**
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- `bitmap` – [Bitmap object](#bitmap_functions-bitmapbuild).
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- `needle` – Searched bit value. Type: [UInt32](../../sql-reference/data-types/int-uint.md).
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**Returned values**
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- 0 — If `bitmap` does not contain `needle`.
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- 1 — If `bitmap` contains `needle`.
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Type: `UInt8`.
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**Example**
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``` sql
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SELECT bitmapContains(bitmapBuild([1,5,7,9]), toUInt32(9)) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 1 │
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└─────┘
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```
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## bitmapHasAny
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Checks whether two bitmaps intersect.
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If `bitmap2` contains exactly one element, consider using [bitmapContains](#bitmap_functions-bitmapcontains) instead as it works more efficiently.
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**Syntax**
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``` sql
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bitmapHasAny(bitmap1, bitmap2)
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```
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**Arguments**
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- `bitmap1` – Bitmap object 1.
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- `bitmap2` – Bitmap object 2.
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**Return values**
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- `1`, if `bitmap1` and `bitmap2` have at least one shared element.
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- `0`, otherwise.
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**Example**
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``` sql
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SELECT bitmapHasAny(bitmapBuild([1,2,3]),bitmapBuild([3,4,5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 1 │
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└─────┘
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```
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## bitmapHasAll
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Returns 1 if the first bitmap contains all elements of the second bitmap, otherwise 0.
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If the second bitmap is empty, returns 1.
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Also see `hasAll(array, array)`.
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**Syntax**
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``` sql
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bitmapHasAll(bitmap1, bitmap2)
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```
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**Arguments**
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- `bitmap1` – Bitmap object 1.
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- `bitmap2` – Bitmap object 2.
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**Example**
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``` sql
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SELECT bitmapHasAll(bitmapBuild([1,2,3]),bitmapBuild([3,4,5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 0 │
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└─────┘
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```
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## bitmapCardinality
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Rerturn the cardinality of a bitmap.
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**Syntax**
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``` sql
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bitmapCardinality(bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapCardinality(bitmapBuild([1, 2, 3, 4, 5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 5 │
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└─────┘
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```
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## bitmapMin
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Computes the smallest bit set in a bitmap, or UINT32_MAX if the bitmap is empty.
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**Syntax**
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```sql
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bitmapMin(bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapMin(bitmapBuild([1, 2, 3, 4, 5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 1 │
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└─────┘
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```
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## bitmapMax
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Computes the greatest bit set in a bitmap, or 0 if the bitmap is empty.
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**Syntax**
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```sql
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bitmapMax(bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapMax(bitmapBuild([1, 2, 3, 4, 5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 5 │
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└─────┘
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```
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## bitmapTransform
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Replaces at most N bits in a bitmap. The old and new value of the i-th replaced bit is given by `from_array[i]` and `to_array[i]`.
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The result depends on the array ordering if `from_array` and `to_array`.
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**Syntax**
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``` sql
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bitmapTransform(bitmap, from_array, to_array)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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- `from_array` – UInt32 array. For idx in range \[0, from_array.size()), if bitmap contains from_array\[idx\], then replace it with to_array\[idx\].
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- `to_array` – UInt32 array with the same size as `from_array`.
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapTransform(bitmapBuild([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]), cast([5,999,2] as Array(UInt32)), cast([2,888,20] as Array(UInt32)))) AS res;
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```
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Result:
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``` text
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┌─res───────────────────┐
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│ [1,3,4,6,7,8,9,10,20] │
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└───────────────────────┘
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```
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## bitmapAnd
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Computes the logical conjunction of two two bitmaps.
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**Syntax**
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``` sql
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bitmapAnd(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapAnd(bitmapBuild([1,2,3]),bitmapBuild([3,4,5]))) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ [3] │
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└─────┘
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```
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## bitmapOr
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Computes the logical disjunction of two bitmaps.
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**Syntax**
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``` sql
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bitmapOr(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapOr(bitmapBuild([1,2,3]),bitmapBuild([3,4,5]))) AS res;
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```
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Result:
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``` text
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┌─res─────────┐
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│ [1,2,3,4,5] │
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└─────────────┘
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```
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## bitmapXor
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Xor-s two bitmaps.
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**Syntax**
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``` sql
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bitmapXor(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapXor(bitmapBuild([1,2,3]),bitmapBuild([3,4,5]))) AS res;
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```
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Result:
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``` text
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┌─res───────┐
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│ [1,2,4,5] │
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└───────────┘
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```
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## bitmapAndnot
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Computes the logical conjunction of two bitmaps and negates the result.
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**Syntax**
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``` sql
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bitmapAndnot(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapToArray(bitmapAndnot(bitmapBuild([1,2,3]),bitmapBuild([3,4,5]))) AS res;
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```
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Result:
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``` text
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┌─res───┐
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│ [1,2] │
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└───────┘
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```
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## bitmapAndCardinality
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Returns the cardinality of the logical conjunction of two bitmaps.
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**Syntax**
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``` sql
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bitmapAndCardinality(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapAndCardinality(bitmapBuild([1,2,3]),bitmapBuild([3,4,5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 1 │
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└─────┘
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```
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## bitmapOrCardinality
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Returns the cardinality of the logical disjunction of two bitmaps.
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``` sql
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bitmapOrCardinality(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapOrCardinality(bitmapBuild([1,2,3]),bitmapBuild([3,4,5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 5 │
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└─────┘
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```
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## bitmapXorCardinality
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Returns the cardinality of the XOR of two bitmaps.
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``` sql
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bitmapXorCardinality(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapXorCardinality(bitmapBuild([1,2,3]),bitmapBuild([3,4,5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 4 │
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└─────┘
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```
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## bitmapAndnotCardinality
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Returns the cardinality of the AND-NOT operation of two bitmaps.
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``` sql
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bitmapAndnotCardinality(bitmap,bitmap)
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```
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**Arguments**
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- `bitmap` – Bitmap object.
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**Example**
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``` sql
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SELECT bitmapAndnotCardinality(bitmapBuild([1,2,3]),bitmapBuild([3,4,5])) AS res;
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```
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Result:
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``` text
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┌─res─┐
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│ 2 │
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└─────┘
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```
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