is there any api I can use to parse create table statement?

[Kant Kodali]

Hi All,

I am wondering if there any API I can use to parse a raw create table (a int primary key , b int) string such that I can use the api to get all columns, primary keys and clustering keys? 

Thanks!

[Alex Ott]

Hi

Do you have only text for this statement, or there is an existing table in the database?

This project (https://github.com/lbruand/cql2plantuml) is using parser written in Scala to parse CQL statements into pieces & generate PlantUML diagrams.

But if you have existing table, then it's much easier - just use Metadata class to retrieve all necessary information...

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[Alex Ott]

Sorry, clicked Send too early...

Another possibility - re-use Cassandra's parser directly, like here: https://github.com/tacoo/cassandra-antlr-sample

[Allan Pomeroy]

Not sure, but you might be able o query that data from one of the system tables.

Sent from my iPad

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[Alex Ott]

com.datastax.driver.core.Metadata is more reliable method that works with different versions of Cassandra...

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[Kant Kodali]

Hi Alex,

I only have the text for the statement so I can't send it to Cassandra first and then read the System tables. This https://github.com/tacoo/cassandra-antlr-sample looks the option I am looking for! 

can I use just this com.datastax.driver.core.Metadata given that I only have text and extract the columns out of it?

Thanks!

[Kant Kodali]

HI Alex,

I used the example from that link you sent. I get the following error. 

Exception in thread "main" org.apache.cassandra.exceptions.ConfigurationException: Keyspace test_keyspace doesn't exist

at org.apache.cassandra.cql3.statements.CreateTableStatement$RawStatement.prepare(CreateTableStatement.java:200)

at com.hello.world.Test.main(Test.java:23)

Here is my code.

package com.hello.world;

import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.CommonTokenStream;
import org.apache.cassandra.cql3.CqlLexer;
import org.apache.cassandra.cql3.CqlParser;
import org.apache.cassandra.cql3.statements.CreateTableStatement;
import org.apache.cassandra.cql3.statements.ParsedStatement;

public class Test {

    public static void main(String[] args) throws Exception {
        String stmt = "create table if not exists test_keyspace.my_table (field1 text, field2 int, field3 set<ascii>, field4 map<ascii, text>, primary key (field1) );";
        ANTLRStringStream stringStream = new ANTLRStringStream(stmt);
        CqlLexer cqlLexer = new CqlLexer(stringStream);
        CommonTokenStream token = new CommonTokenStream(cqlLexer);
        CqlParser parser = new CqlParser(token);
        ParsedStatement query = parser.query();
        if (query.getClass().getDeclaringClass() == CreateTableStatement.class) {
            CreateTableStatement.RawStatement cts = (CreateTableStatement.RawStatement) query;
            System.out.println(cts.keyspace());
            System.out.println(cts.columnFamily());
            ParsedStatement.Prepared prepared = cts.prepare();
            CreateTableStatement cts2 = (CreateTableStatement) prepared.statement;
            cts2.getCFMetaData()
                    .getColumnMetadata()
                    .values()
                    .stream()
                    .forEach(cd -> System.out.println(cd));
        }
    }
}

Thanks!

[Jens Teglhus Møller]

Hi

If you include cassandra as a dependency in your project, you can use the lexer that comes with it. I did it for a prototype i have for parsing full statements in the cassandra-maven-plugin, it is quite simple.

Below is a snippet that parses a full cql file into statements (instead of the current split in ; which breaks badly if you have ; in a string or comment).

protected static String[] splitStatementsUsingCqlLexer(String statements) {
    ANTLRStringStream stream = new ANTLRStringStream(statements);
    CqlLexer lexer = new CqlLexer(stream);
    ArrayList<String> statementList = new ArrayList<String>();
    StringBuffer currentStatement = new StringBuffer();
    boolean inComment;
    // Not the prettiest code i ever wrote, but it gets the job done.
    for (Token token = lexer.nextToken(); token.getType() != Token.EOF; token = lexer.nextToken()) {
        if (token.getText().equals(";")) {
            // when we meet a ; terminate current statement and prepare the next
            currentStatement.append(";");
            statementList.add(currentStatement.toString());
            currentStatement = new StringBuffer();
        } else if (token.getType() == CqlLexer.STRING_LITERAL) {
            // If we meet a string we should quote it and escape any enclosed ' as ''
            currentStatement.append("'");
            // TODO: There must be a cassandra util method somewhere that escapes a string for sql
            currentStatement.append(token.getText().replaceAll("'", "''"));
            currentStatement.append("'");
        } else {
            currentStatement.append(token.getText());
        }
    }
    if (currentStatement.length() > 0 && currentStatement.toString().trim().length() > 0) {
        statementList.add(currentStatement.toString());
    }
    return statementList.toArray(new String[statementList.size()]);
}

Best regards Jens

[Jens Teglhus Møller]

Ok, next time I will read the full thread before answering ;-)

[Jens Teglhus Møller]

Hi Kant

I think the error message does a pretty decent job at describing the problem. You need to create the keyspace before you can add table to it. See https://docs.datastax.com/en/cql/3.3/cql/cql_reference/cqlCreateKeyspace.html for details.

Best regards Jens

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With best wishes,                    Alex Ott
http://alexott.net/
Twitter: alexott_en (English), alexott (Russian)
Skype: alex.ott

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With best wishes,                    Alex Ott
http://alexott.net/
Twitter: alexott_en (English), alexott (Russian)
Skype: alex.ott

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