ydb-sqlglot-plugin

YDB dialect plugin for sqlglot — transpiles SQL from any dialect into YDB/YQL.

Installation

pip install ydb-sqlglot-plugin

Usage

After installing the package, the ydb dialect is available in sqlglot automatically — no extra imports needed:

import sqlglot

# Transpile from any dialect
result = sqlglot.transpile("SELECT * FROM users WHERE id = 1", read="mysql", write="ydb")[0]
# → SELECT * FROM `users` WHERE id = 1

# Or parse first, then generate
query = "SELECT * FROM orders WHERE user_id = 1"
parsed = sqlglot.parse_one(query, dialect="postgres")
yql = parsed.sql(dialect="ydb")

What the plugin does

Table names

Database-qualified names are rewritten to the YDB path format and wrapped in backticks:

-- input
SELECT * FROM analytics.events

-- output
SELECT * FROM `analytics/events`

CTEs → YDB variables

-- input
WITH active AS (SELECT * FROM users WHERE status = 'active')
SELECT * FROM active

-- output
$active = (SELECT * FROM `users` WHERE status = 'active');

SELECT * FROM $active AS active

Subquery decorrelation

Correlated subqueries (which YQL does not support) are rewritten as JOINs:

-- input
SELECT id, (SELECT MAX(amount) FROM orders WHERE orders.user_id = users.id) AS max_order
FROM users

-- output
SELECT users.id AS id, _u_0._u_2 AS max_order
FROM `users`
LEFT JOIN (
    SELECT MAX(amount) AS _u_2, user_id AS _u_1
    FROM `orders`
    WHERE TRUE
    GROUP BY user_id AS _u_1
) AS _u_0 ON users.id = _u_0._u_1

The same rewriting applies to EXISTS, IN (subquery), and ANY/ALL subqueries.

---

Function reference

Functions below are recognized by sqlglot as standard SQL expressions and translated to their YQL equivalents. Dialect-specific functions that sqlglot does not parse into typed AST nodes are passed through unchanged — see Limitations.

Date / time

Input	YQL output
DATE_TRUNC('day', x)	DATE(x)
DATE_TRUNC('week', x)	DateTime::MakeDate(DateTime::StartOfWeek(x))
DATE_TRUNC('month', x)	DateTime::MakeDate(DateTime::StartOfMonth(x))
DATE_TRUNC('quarter', x)	DateTime::MakeDate(DateTime::StartOfQuarter(x))
DATE_TRUNC('year', x)	DateTime::MakeDate(DateTime::StartOfYear(x))
EXTRACT(WEEK FROM x)	DateTime::GetWeekOfYear(x)
EXTRACT(MONTH FROM x)	DateTime::GetMonth(x)
EXTRACT(YEAR FROM x)	DateTime::GetYear(x)
CURRENT_TIMESTAMP	CurrentUtcTimestamp()
STR_TO_DATE(str, fmt) / TO_DATE(str, fmt)	DateTime::MakeTimestamp(DateTime::Parse(fmt)(str))
DATE_ADD(x, INTERVAL n MONTH)	DateTime::MakeDate(DateTime::ShiftMonths(x, n))
DATE_ADD(x, INTERVAL n YEAR)	DateTime::MakeDate(DateTime::ShiftYears(x, n))
DATE_ADD(x, INTERVAL n DAY)	x + DateTime::IntervalFromDays(n)
DATE_ADD(x, INTERVAL n HOUR)	x + DateTime::IntervalFromHours(n)
DATE_ADD(x, INTERVAL n MINUTE)	x + DateTime::IntervalFromMinutes(n)
DATE_ADD(x, INTERVAL n SECOND)	x + DateTime::IntervalFromSeconds(n)
DATE_SUB(x, INTERVAL n ...)	same as DATE_ADD with −
INTERVAL n DAY (literal)	DateTime::IntervalFromDays(n)
INTERVAL n HOUR (literal)	DateTime::IntervalFromHours(n)
INTERVAL n MINUTE (literal)	DateTime::IntervalFromMinutes(n)
INTERVAL n SECOND (literal)	DateTime::IntervalFromSeconds(n)
dateDiff('minute', a, b)	(CAST(b AS Int64) - CAST(a AS Int64)) / 60000000
dateDiff('hour', a, b)	(CAST(b AS Int64) - CAST(a AS Int64)) / 3600000000
dateDiff('day', a, b)	(CAST(b AS Int64) - CAST(a AS Int64)) / 86400000000
dateDiff('week', a, b)	(CAST(b AS Int64) - CAST(a AS Int64)) / 604800000000

Note on dateDiff: YDB stores Timestamp as microseconds since epoch. The formula above gives exact integer units assuming both arguments are Timestamp. Results for Date-typed columns will differ.

Strings

Input	YQL output
CONCAT(a, b, ...)	a || b || ...
UPPER(x)	Unicode::ToUpper(x)
LOWER(x)	Unicode::ToLower(x)
LENGTH(x) / CHAR_LENGTH(x)	Unicode::GetLength(x)
POSITION(sub IN x) / STRPOS(x, sub)	Find(x, sub)
STRING_TO_ARRAY(x, delim)	String::SplitToList(x, delim)
ARRAY_TO_STRING(arr, delim)	String::JoinFromList(arr, delim)

Arrays / collections

Input	YQL output
ARRAY(v1, v2, ...)	AsList(v1, v2, ...)
ARRAY_LENGTH(x) / ARRAY_SIZE(x)	ListLength(x)
ARRAY_FILTER(arr, x -> cond)	ListFilter(arr, ($x) -> {RETURN cond})
ARRAY_ANY(arr, x -> cond)	ListHasItems(ListFilter(arr, ($x) -> {RETURN cond}))
ARRAY_AGG(x)	AGGREGATE_LIST(x)
UNNEST(x)	FLATTEN BY x

Conditional / math

Input	YQL output
NULLIF(x, y)	IF(x = y, NULL, x)
ROUND(x, n)	Math::Round(x, -n)
COUNT() (zero-argument form)	COUNT(*)

JSON

Input	YQL output
jsonb_col @> value (PostgreSQL)	Yson::Contains(jsonb_col, value)

---

Type mapping

SQL type	YQL type
TINYINT	INT8
SMALLINT	INT16
INT / INTEGER	INT32
BIGINT	INT64
FLOAT	Float
DOUBLE / DOUBLE PRECISION	Double
DECIMAL(p, s)	Decimal(p, s)
BOOLEAN / BIT	Uint8
TIMESTAMP	Timestamp
VARCHAR / NVARCHAR / CHAR	Utf8
TEXT / TINYTEXT / MEDIUMTEXT / LONGTEXT	Utf8
BLOB / TINYBLOB / MEDIUMBLOB / LONGBLOB / VARBINARY	String

---

Limitations

Correlated subqueries in DML

Correlated subqueries inside UPDATE or INSERT statements cannot be automatically decorrelated — YDB does not support them natively, and rewriting requires knowledge of the table's primary key. Rewrite manually using a $variable:

-- not supported (will raise an error)
UPDATE t SET col = (SELECT val FROM other WHERE other.id = t.id)

-- workaround
$vals = (SELECT id, val FROM other);
UPDATE t SET col = (SELECT val FROM $vals WHERE id = t.id)

Correlated subqueries inside SELECT are handled automatically via JOIN rewriting.

dateDiff with month granularity

dateDiff('month', a, b) has no exact equivalent in YDB because months have variable length. Use DateTime::ShiftMonths for date arithmetic instead.

---

Development

git clone https://github.com/ydb-platform/ydb-sqlglot-plugin.git
cd ydb-sqlglot-plugin
python -m venv .venv && source .venv/bin/activate
pip install -e ".[dev]"
python -m pytest tests/