--- title: "ilike_escape" slug: "dev-database-reference-sql-functions-string-ilike-escape" updated: 2026-10-30T18:18:56Z published: 2026-10-30T18:18:56Z canonical: "docs.vastdata.com/dev-database-reference-sql-functions-string-ilike-escape" --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.vastdata.com/llms.txt > Use this file to discover all available pages before exploring further. # ilike_escape *Applies to VAST Cluster 5.5.* *[Functions](/develop/docs/dev-database-reference-sql-functions-index) › [Search and split](/develop/docs/dev-database-reference-sql-functions-string-search-and-split) › Pattern matching.* `ilike_escape(s, pattern, escape)` is the function form of `s ILIKE pattern ESCAPE escape`: true if the whole string matches a [LIKE](/develop/docs/dev-database-reference-sql-functions-string-like) pattern, ignoring case, where the escape character makes the next `%` or `_` literal. `not_ilike_escape` returns the opposite, like `NOT ILIKE ... ESCAPE`. ## Syntax ``` ilike_escape(s, pattern, escape) not_ilike_escape(s, pattern, escape) ``` | Argument | Type | Description | | --- | --- | --- | | `s` | `VARCHAR` | The string to test. | | `pattern` | `VARCHAR` | A [LIKE](/develop/docs/dev-database-reference-sql-functions-string-like) pattern: `%` matches any run of characters, `_` exactly one. Case is ignored. | | `escape` | `VARCHAR` | Empty, or one ASCII character. In the pattern, it makes the next `%`, `_` or escape character literal. | **Returns:** `BOOLEAN`. **Related:** `s ILIKE pattern ESCAPE escape` and `s NOT ILIKE pattern ESCAPE escape` give the same results; for a case-sensitive match, use [like_escape](/develop/docs/dev-database-reference-sql-functions-string-like-escape). ## Set up the examples The examples connect with the ADBC driver, as in [VAST Query Engine (ADBC)](/develop/docs/dev-database-integrations-adbc), and work in a schema called `docs_sql_fn_string_ilike_escape`. Set `QE_ENDPOINT`, `AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY` and `VASTDB_BUCKET` ([SQL reference](/develop/docs/dev-database-reference-sql-index#example-connect-and-use-a-transaction)), and run the blocks in order in one Python session. Below each block is the output you should see. This block connects, defines the `run()` and `plan()` helpers, and creates a table of five file paths in mixed case. Rows 1 and 3 have a literal `_` or `%` in their names; rows 2 and 4 are the same names with another character in that place. The last row has no values: ``` import os import re import adbc_driver_manager import adbc_driver_manager.dbapi as dbapi import adbc_driver_vastdb BUCKET = os.environ["VASTDB_BUCKET"] SCHEMA = f'"{BUCKET}/docs_sql_fn_string_ilike_escape"' conn = dbapi.connect( driver=adbc_driver_vastdb.get_driver_path(), db_kwargs={ "vast.db.endpoint": os.environ["QE_ENDPOINT"], "vast.db.access_key": os.environ["AWS_ACCESS_KEY_ID"], "vast.db.secret_key": os.environ["AWS_SECRET_ACCESS_KEY"], }, autocommit=True, ) def server_message(e): """The server's message in a driver error, without the request ID or the echoed statement.""" text = re.sub(r"\[req=0x[0-9a-f]+\]: ", "", str(e)) found = (re.search(r'message: "(.*?)", request_id', text, re.S) or re.search(r"description: (.*)\)", text, re.S)) message = found.group(1) if found else text.strip().splitlines()[-1] message = re.sub(r"^Plan query: '.*?' failed with: ", "", message, flags=re.S) message = re.split(r"\\n|\n", message)[0].replace('\\"', '"') return message.replace(BUCKET, "") def run(sql): """Run one statement. Print the rows it returns, or the error.""" try: with conn.cursor() as cur: cur.execute(sql) rows = cur.fetchall() if cur.description else [] except (adbc_driver_manager.Error, OSError) as e: print(f"{type(e).__name__}: {server_message(e)}") else: print(rows) def plan(sql): """Print the plan without its ~N Rows lines: the table's row count, which can still be 0 just after an insert.""" with conn.cursor() as cur: cur.execute("EXPLAIN " + sql) steps = cur.fetchall()[0][1] print("\n".join(line for line in steps.splitlines() if "Rows" not in line)) TABLE = f"{SCHEMA}.files" run(f"CREATE SCHEMA IF NOT EXISTS {SCHEMA}") run(f"CREATE TABLE IF NOT EXISTS {TABLE} (id BIGINT, path VARCHAR)") run(f"INSERT INTO {TABLE} VALUES " "(1, '/Data/Run_1.TXT'), " "(2, '/data/runx1.txt'), " "(3, '/TMP/Load_50%.csv'), " "(4, '/tmp/load_50x.CSV'), " "(5, NULL)") ``` ``` [] [] [(5,)] ``` ## What it does `ilike_escape(s, pattern, escape)` gives the same result as `s ILIKE pattern ESCAPE escape`, and `not_ilike_escape` the same as `s NOT ILIKE pattern ESCAPE escape`. The pattern works as for [like_escape](/develop/docs/dev-database-reference-sql-functions-string-like-escape), but upper and lower case match each other: | In the pattern (escape `$`) | Matches | Example | Result | | --- | --- | --- | --- | | `%`, `_` | any run of characters; exactly one character | `ilike_escape('Ab', 'a%', '$')` | `true` | | Letters | the same letter in either case | `ilike_escape('AB', 'ab', '$')` | `true` | | `$%`, `$_` | a literal `%` or `_` | `ilike_escape('a%b', 'a$%b', '$')` | `true` | | `$$` | a literal `$` | `ilike_escape('a$b', 'a$$b', '$')` | `true` | | `$` at the end of the pattern | nothing | `ilike_escape('ab', 'ab$', '$')` | `false` | - **The match covers the whole string,** as for [ILIKE](/develop/docs/dev-database-reference-sql-functions-string-ilike). Put `%` at both ends to match anywhere in it. - **An empty escape means no escape character:** `%` and `_` are always wildcards. - **Choose an escape character that isn't in your data,** such as `$` or `!`. A backslash works too: `ilike_escape('a_b', 'a\_b', '\')` is true. - **`_` matches one code point.** A precomposed `é` matches `_`; `e` followed by a combining accent is two code points and doesn't. ## NULLs and edge cases | Input | Result | | --- | --- | | `NULL` as any of the three arguments | `NULL` | | `ilike_escape('', '', '$')`, `ilike_escape('', '%', '$')` | `true` | | `ilike_escape('ab', 'ab', '')` (no escape character) | `true` | | `ilike_escape('axb', 'a$%b', '$')`, `ilike_escape('axb', 'a$_b', '$')` | `false` | | `ilike_escape('a', 'a$', '$')` (pattern ends with the escape character) | `false` | | `ilike_escape('a_b', 'a\_b', '\')` | `true` | | `ilike_escape('é', '_', '$')` (precomposed) | `true` | | `ilike_escape('e\u0301', '_', '$')` (`e` and a combining accent: two code points) | `false` | | `ilike_escape('a%', 'a%%', '%')` (`%` as the escape character) | `true` | | `ilike_escape('a\nb', 'a_b', '$')` (a newline in the string) | `true` | | `not_ilike_escape('a%b', 'a$%b', '$')`, `not_ilike_escape('AB', 'ab', '$')` | `false` | | An escape of two characters, or a non-ASCII one such as `é` | Error: `Invalid escape string. Escape string must be empty or one character.` | The same cases, as the cluster returns them. They use the table and helpers from [Set up the examples](/develop/docs/dev-database-reference-sql-functions-string-ilike-escape#set-up-the-examples): ``` run("SELECT ilike_escape(NULL, 'a', '$'), ilike_escape('a', NULL, '$'), ilike_escape('a', 'a', NULL), " "ilike_escape('', '', '$'), ilike_escape('', '%', '$'), ilike_escape('ab', 'ab', '')") run("SELECT ilike_escape('axb', 'a$%b', '$'), ilike_escape('axb', 'a$_b', '$'), ilike_escape('a', 'a$', '$'), " "ilike_escape('a_b', 'a\\_b', '\\'), ilike_escape('a%', 'a%%', '%')") run("SELECT ilike_escape('\u00e9', '_', '$'), ilike_escape('e\u0301', '_', '$'), ilike_escape('a\nb', 'a_b', '$')") run("SELECT not_ilike_escape('a%b', 'a$%b', '$'), not_ilike_escape('AB', 'ab', '$'), not_ilike_escape('axb', 'a$%b', '$')") run("SELECT ilike_escape('ab', 'a_', '$$')") run("SELECT ilike_escape('ab', 'ab', '\u00e9')") ``` ``` [(None, None, None, True, True, True)] [(False, False, False, True, True)] [(True, False, True)] [(False, False, True)] OSError: Invalid escape string. Escape string must be empty or one character. OSError: Invalid escape string. Escape string must be empty or one character. ``` ## Examples Without escaping, `_` is a wildcard, so `ILIKE '%run_1%'` matches rows 1 and 2. With `$` as the escape character, only the literal `_` matches, in any case. The `ILIKE ... ESCAPE` form gives the same result: ``` run(f"SELECT id, path ILIKE '%run_1%', ilike_escape(path, '%run$_1%', '$'), path ILIKE '%run$_1%' ESCAPE '$' " f"FROM {TABLE} ORDER BY id LIMIT 10") ``` ``` [(1, True, True, True), (2, True, False, False), (3, False, False, False), (4, False, False, False), (5, None, None, None)] ``` Keep the files under `/tmp/`, in any case, whose name has a literal `%`, and those that don't: ``` run(f"SELECT id, path FROM {TABLE} WHERE ilike_escape(path, '/tmp/%$%%', '$') ORDER BY id LIMIT 10") run(f"SELECT id, path FROM {TABLE} WHERE not_ilike_escape(path, '/tmp/%$%%', '$') ORDER BY id LIMIT 10") ``` ``` [(3, '/TMP/Load_50%.csv')] [(1, '/Data/Run_1.TXT'), (2, '/data/runx1.txt'), (4, '/tmp/load_50x.CSV')] ``` ## How it runs in VAST The Query Engine runs on the cluster's CNodes, and a query on a table starts with a scan in VAST DataBase (`VAST_SCAN`). VAST DataBase can evaluate a comparison of a column with a constant, but not a pattern match, so `ilike_escape()` is always computed by the Query Engine: - **In the `SELECT` list,** the scan reads the column and the Query Engine computes `ilike_escape()` for each row it returns. - **In `WHERE`,** the scan sends the column for every row, and a `FILTER` step in the Query Engine keeps the rows that match. No rows are skipped in storage. A prefix pattern isn't rewritten to a cheaper test: `ilike_escape(path, '/tmp/%', '$')` stays `ilike_escape` in the plan. The plan of the `WHERE` example: ``` plan(f"SELECT id FROM {TABLE} WHERE ilike_escape(path, '/tmp/%$%%', '$')") ``` ``` ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #1 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ilike_escape(path, '/tmp/%│ │ $%%', '$') │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ path │ │ id │ │ │ └───────────────────────────┘ ``` ## Make it faster - **Store the case you search on.** If you often match without regard to case, store a lower-case copy of the column when you write the rows. A comparison of that column with a lower-case constant, such as `path_lower = '/tmp/load_50%.csv'`, is pushed down to VAST DataBase, so rows that don't match never leave storage. - **Use `contains()` for a literal substring.** To find a literal `%` or `_` anywhere, [contains](/develop/docs/dev-database-reference-sql-functions-string-contains)`(path, '%')` needs no escape character at all; `%`, `_` and letters have no special meaning there, and case counts. - **Combine it with a pushed-down condition.** In `id > 2 AND ilike_escape(path, '%$%%', '$')`, `id > 2` is still evaluated in VAST DataBase, so `ilike_escape()` runs only on the rows that pass it. ``` run(f"SELECT id, contains(path, '%'), ilike_escape(path, '%$%%', '$') FROM {TABLE} ORDER BY id LIMIT 10") plan(f"SELECT id FROM {TABLE} WHERE id > 2 AND ilike_escape(path, '%$%%', '$')") ``` ``` [(1, False, False), (2, False, False), (3, True, True), (4, False, False), (5, None, None)] ┌───────────────────────────┐ │ PROJECTION │ │ ──────────────────── │ │ #0 │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ FILTER │ │ ──────────────────── │ │ ilike_escape(path, '%$%%',│ │ '$') │ │ │ └─────────────┬─────────────┘ ┌─────────────┴─────────────┐ │ VAST_SCAN │ │ ──────────────────── │ │ Function: VAST_SCAN │ │ │ │ Projections: │ │ id │ │ path │ │ │ └───────────────────────────┘ ``` ## Limitations and errors - **The escape is empty or one ASCII character.** Two characters, or one non-ASCII character such as `é`, fail with `Invalid escape string. Escape string must be empty or one character.` An escape taken from a column fails the same way if any row holds a longer value. - **A pattern can't end with the escape character when it is `%`.** `ilike_escape('ab', 'a%', '%')` fails with `Like pattern must not end with escape character!`. With another escape character, `ilike_escape('a', 'a$', '$')` is false and doesn't fail. - **All three arguments are strings.** A number as the escape fails with `No function matches the given name and argument types 'ilike_escape(STRING_LITERAL, STRING_LITERAL, INTEGER_LITERAL)'`; a number, date, boolean, `BLOB` or list as the string fails the same way. Cast a value to `VARCHAR` first. ``` run("SELECT ilike_escape('ab', 'a%', '%')") run("SELECT ilike_escape('ab', 'ab', 1)") run("SELECT ilike_escape(CAST(123 AS VARCHAR), '1%', '$')") ``` ``` OSError: Like pattern must not end with escape character! InternalError: Binder Error: No function matches the given name and argument types 'ilike_escape(STRING_LITERAL, STRING_LITERAL, INTEGER_LITERAL)'. You might need to add explicit type casts. [(True,)] ``` ## Similar functions | Function | Same as | Case | | --- | --- | --- | | `ilike_escape(s, p, e)` | `s ILIKE p ESCAPE e` | ignored | | `not_ilike_escape(s, p, e)` | `s NOT ILIKE p ESCAPE e` | ignored | | [like_escape](/develop/docs/dev-database-reference-sql-functions-string-like-escape) `(s, p, e)` | `s LIKE p ESCAPE e` | sensitive | | [ILIKE](/develop/docs/dev-database-reference-sql-functions-string-ilike) | `ilike_escape` with no escape character | ignored | | [contains](/develop/docs/dev-database-reference-sql-functions-string-contains) | `LIKE '%text%'` with every character literal | sensitive | ``` run("SELECT ilike_escape('A%B', 'a$%b', '$'), 'A%B' ILIKE 'a$%b' ESCAPE '$', not_ilike_escape('A%B', 'a$%b', '$'), " "like_escape('A%B', 'a$%b', '$'), 'A%B' ILIKE 'a%b', contains('A%B', '%')") ``` ``` [(True, True, False, False, True, True)] ``` Clean up: ``` run(f"DROP TABLE IF EXISTS {TABLE}") run(f"DROP SCHEMA IF EXISTS {SCHEMA}") conn.close() ``` ``` [] [] ``` ## See also - [Search and split](/develop/docs/dev-database-reference-sql-functions-string-search-and-split): all the search and pattern functions. - [like_escape](/develop/docs/dev-database-reference-sql-functions-string-like-escape), [ILIKE](/develop/docs/dev-database-reference-sql-functions-string-ilike) and [LIKE](/develop/docs/dev-database-reference-sql-functions-string-like). - [Operators and predicates](/develop/docs/dev-database-reference-sql-functions-operators-and-predicates#pattern-matching). - [Where filters run](/develop/docs/dev-database-reference-sql-select#where-filters-run) and [pushdowns](/develop/docs/dev-database-reference-pushdowns). - [EXPLAIN](/develop/docs/dev-database-reference-sql-explain): how to read a plan.