[IMPALA-9817] Document flags of Fetch-on-demand metadata coordinators

• Type: Documentation
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: Impala 4.0.0
• Component/s: Docs
• Epic Color: ghx-label-14
• Assignee: shajini thayasingh
• Reporter: Quanlong Huang
• Created: 02/Jun/20 02:52
• Updated: 23/Jun/20 01:19
• Resolved: 23/Jun/20 01:19

Description

We need to document about these flags: 

DEFINE_bool_hidden(use_local_catalog, false,
    "Use experimental implementation of a local catalog. If this is set, "
    "the catalog service is not used and does not need to be started.");
DEFINE_int32_hidden(local_catalog_cache_mb, -1,
    "If --use_local_catalog is enabled, configures the size of the catalog "
    "cache within each impalad. If this is set to -1, the cache is auto-"
    "configured to 60% of the configured Java heap size. Note that the Java "
    "heap size is distinct from and typically smaller than the overall "
    "Impala memory limit.");
DEFINE_int32_hidden(local_catalog_cache_expiration_s, 60 * 60,
    "If --use_local_catalog is enabled, configures the expiration time "
    "of the catalog cache within each impalad. Even if the configured "
    "cache capacity has not been reached, items are removed from the cache "
    "if they have not been accessed in this amount of time.");
DEFINE_int32_hidden(local_catalog_max_fetch_retries, 40,
    "If --use_local_catalog is enabled, configures the maximum number of times "
    "the frontend retries when fetching a metadata object from the impalad "
    "coordinator's local catalog cache."); 

https://github.com/apache/impala/blob/052129c16a29891a72427b351bcc4e087d772fbe/be/src/runtime/exec-env.cc#L103-L120

Issue Links

• is related to: IMPALA-7127 Fetch-on-demand metadata for the impalad-side catalog
• relates to: IMPALA-9823 use_local_catalog and related flags shouldn't be hidden