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Sharing Macros

DuckDB has a powerful macro mechanism that allows creating shorthands for common tasks.

Sharing a Scalar Macro

First, we defined a macro that pretty-prints a non-negative integer as a short string with thousands, millions, and billions (without rounding) as follows:

duckdb pretty_print_integer_macro.duckdb

CREATE MACRO pretty_print_integer(n) AS
    CASE
        WHEN n >= 1_000_000_000 THEN printf('%dB', n // 1_000_000_000)
        WHEN n >= 1_000_000     THEN printf('%dM', n // 1_000_000)
        WHEN n >= 1_000         THEN printf('%dk', n // 1_000)
        ELSE printf('%d', n)
    END;

SELECT pretty_print_integer(25_500_000) AS x;

┌─────────┐
│    x    │
│ varchar │
├─────────┤
│ 25M     │
└─────────┘

As one would expect, the macro gets persisted in the database. But this also means that we can host it on an HTTPS endpoint and share it with anyone! We have published this macro on blobs.duckdb.org.

You can try it from DuckDB:

duckdb

Make sure that the httpfs extension is installed:

INSTALL httpfs;

You can now attach to the remote endpoint and use the macro:

ATTACH 'https://blobs.duckdb.org/data/pretty_print_integer_macro.duckdb'
    AS pretty_print_macro_db;

SELECT pretty_print_macro_db.pretty_print_integer(42_123) AS x;

┌─────────┐
│    x    │
│ varchar │
├─────────┤
│ 42k     │
└─────────┘

Sharing a Table Macro

It's also possible to share table macros. For example, we created the checksum macro as follows:

duckdb compute_table_checksum.duckdb

CREATE MACRO checksum(table_name) AS TABLE
    SELECT bit_xor(md5_number(COLUMNS(*)::VARCHAR))
    FROM query_table(table_name);

To use it, make sure that the httpfs extension is installed:

INSTALL httpfs;

You can attach to the remote endpoint and use the macro:

ATTACH 'https://blobs.duckdb.org/data/compute_table_checksum.duckdb'
    AS compute_table_checksum_db;

CREATE TABLE stations AS
    FROM 'https://blobs.duckdb.org/stations.parquet';

.mode line
FROM compute_table_checksum_db.checksum('stations');

         id = -132780776949939723506211681506129908318
       code = 126327004005066229305810236187733612209
        uic = -145623335062491121476006068124745817380
 name_short = -114540917565721687000878144381189869683
name_medium = -568264780518431562127359918655305384
  name_long = 126079956280724674884063510870679874110
       slug = -53458800462031706622213217090663245511
    country = 143068442936912051858689770843609587944
       type = 5665662315470785456147400604088879751
    geo_lat = 160608116135251821259126521573759502306
    geo_lng = -138297281072655463682926723171691547732
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