What does parsing a query mean?

Question

Most relational databases handles a JDBC / SQL query in four steps:

1. Parse the incoming SQL query
2. Compile the SQL query
3. Plan/optimize the da

Answer 1

1) Parsing: syntactic analysis of the query according to the SQL grammar rules, etc. and attempting to "tokenize" the query into the elementary parts form.

2) Planning/optimization: at that stage the SQL engine tries to evaluate what the best way to execute your query would be. It tries to take advantage of existing indexes, clusters and table relationships; find ways around full table scans, utilize caching effectively by avoiding repeated data reads, and so forth.