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This error is a

java.lang.StackOverflowError

occurring in the StarRocks Frontend (FE) during the SQL parsing phase. It specifically happens when the ANTLR4 parser (the component that reads your SQL) encounters a query that is too complex for the current thread stack size to handle. Why this happens The parser uses a recursive approach to process SQL expressions. If your query has deeply nested structures, the Java Virtual Machine (JVM) runs out of stack space. Common triggers include: * Extremely long

IN

clauses (e.g., tens of thousands of values). * Deeply nested function calls (e.g.,

func(func(func(...)))

). * A large number of

OR

or

AND

conditions in a single

WHERE

clause. * Generated SQL from BI tools or ORMs that produce massive, repetitive expressions. How to fix it 1. Increase the FE Stack Size (Recommended Workaround) You can increase the memory allocated to each thread's stack by adjusting the

-Xss

parameter in your FE configuration. 1. Open your FE configuration file:

fe/conf/fe.conf

. 2. Look for the

JAVA_OPTS

line. 3. Add or increase the

-Xss

value. For example, if it is not set or set to

1m

, try increasing it to

2m

or `4m`:

bash
    # Example setting in fe.conf
    JAVA_OPTS="-Xmx8192m -Xss4m ..."

4. Restart the FE for the changes to take effect. 2. Simplify the Query If possible, refactor the SQL to reduce nesting depth: * Instead of a massive

IN

list or many

OR

conditions, consider loading the values into a temporary table and using a

JOIN

. * Break down complex logic into multiple CTEs (Common Table Expressions) or temporary tables, though the parser still has to process the full statement, so flatting the logic is often more effective than just using CTEs. 3. Check for Version Specific Limits In some StarRocks versions, there are session variables that can limit expression depth to prevent the FE from crashing, though they usually return a "nesting too deep" error rather than a raw

StackOverflowError

. * You can try setting

max_allowed_in_element_num_count

if the issue is specifically related to

IN

clauses, although increasing

-Xss

is the most direct fix for this specific stack trace. If the error persists even with a larger

-Xss

(e.g., 8m or 16m), it is likely a bug or a query that is excessively large and should be redesigned. References • faq/operation_maintenance_faq.md • knowledge/usage/best-practice.md • unloading/arrow_flight.md • knowledge/trouble_shooting/fe_deadlock_problems.md

@Rocky there are too many view chain and can it be a problem?

Yes, having too many links in a view chain (nested views) is a common cause of the

java.lang.StackOverflowError

you encountered. Why it is a problem: 1. Parsing & Expansion (The Cause of your Error): When you query a view, StarRocks must "expand" it into its underlying SQL. If View A depends on View B, which depends on View C, and so on, the FE parser expands these recursively. A very deep chain causes the parser to exceed the JVM stack depth, leading to the

StackOverflowError

you saw. 2. Optimizer Complexity: Each layer of nesting adds complexity to the query optimizer. If the chain is too long, the optimizer may struggle to find the best execution plan, leading to extremely long "planning time" or inefficient queries. 3. Performance Overhead: Logical views are computed in real-time. A deep chain often involves multiple layers of JOINs and aggregations that the database must unwind every single time the query runs. 4. Maintenance: Deeply nested views are hard to debug. A change in a base table at the bottom of the chain can break multiple layers above it or cause unexpected performance drops that are difficult to trace. Recommendations: * Limit Nesting Depth: As a best practice, StarRocks recommends keeping nested layers to 3 or fewer. * Use Asynchronous Materialized Views (MVs): If you have a complex logic chain that is slow or causing errors, consider breaking the chain with an Asynchronous Materialized View. MVs store the physical result of a query, which "cuts" the recursion—the parser only needs to look at the MV's stored result rather than expanding the 10 views behind it. * Increase FE Stack Size: As mentioned previously, you can temporarily bypass the error by increasing

-Xss

in

fe.conf

(e.g., to

4m

or

8m

), but this is a band-aid. The root cause remains the query complexity. * Flatten the Logic: If possible, rewrite the final view to reference the base tables directly or use fewer intermediate steps. Relevant Settings: *

nested_mv_rewrite_max_level

: (Default: 3) Controls how many levels of nested MVs the optimizer will consider for query rewrite. * FE

JAVA_OPTS

: Increase

-Xss

to allow deeper recursion during parsing. In short: Your error is a direct signal that the view chain is too deep for the default FE settings. You should ideally flatten your view logic.** References • knowledge/usage/best-practice.md • using_starrocks/async_mv/Materialized_view.md • administration/management/FE_configuration.md • using_starrocks/async_mv/use_cases/query_rewrite_with_materialized_views.md • using_starrocks/async_mv/use_cases/data_modeling_with_materialized_views.md