Underscores

Remove Underscore Parameters not only before you upgrade

Remove Underscore Parameters not only before you upgradeUnderscore parameters are a wonderful thing in Oracle. They are treated like a secret. But you can view them of course. Everybody can. Make a guess how many underscore parameters exist in Oracle 12.2.0.1.0. You’ll find the answer at the end of this blog post. But why should you remove underscore parameters not only before you upgrade?

I’d like to explain below why underscores, especially too many of them, may cause a lot of trouble. Therefore, housekeeping is very important.

Remove Underscore Parameters not only before you upgrade

This is from a recent upgrade from Oracle 12.1.0.2 to Oracle 12.2.0.1 … [ Read more ]

Oracle 12.2 underscores appear in SPFILE – be aware when you flashback

Oracle 12.2 underscores appear in SPFILE - be aware when you flashbackI did blog in the past weeks about Fallback Strategies with Flashback Database. But two of my reference customers came across an interesting issue when they tried to fallback: Oracle 12.2 underscores appear in the SPFILE – magically – and prevent the fallback using the existing SPFILE.

Oracle 12.2 underscores appear in SPFILE – be aware when you flashback

In one case it happened during a test, in the other case it happened during a live fallback after the Data Guard Broker has interfered with the upgrade causing real trouble. In both cases the SPFILE sits in ASM.

Both … [ Read more ]

Obsolete SPFILE Parameters in Oracle Database 12.2.0.1

This is the 2nd posting in my series about init.ora/SPFILE parameters in Oracle Database 12.2.0.1.

Find the list of the 159 obsoleted parameters here (and of course in V$OBSOLETE_PARAMETERS):

_app_ctx_vers
_average_dirties_half_life
_aw_row_source_enabled
_compatible_no_recovery
_data_transfer_cache_size
_db_no_mount_lock
_dlm_send_timeout
_dtree_bintest_id
_dtree_compressbmp_enabled
_evolve_plan_baseline_report_level
_fast_start_instance_recovery_target
_fic_max_length
_fic_outofmem_candidates
_idl_conventional_index_maintenance
_kgl_latch_count
_kks_free_cursor_stat_pct
_kspptbl_mem_usage
_lm_direct_sends
_lm_multiple_receivers
_lm_rcv_buffer_size
_lm_statistics
_log_archive_buffer_size
_log_io_size
_max_log_write_io_parallelism
_module_action_old_length
_optimizer_adaptive_plans
_optimizer_choose_permutation
_oracle_trace_events
_oracle_trace_facility_version
_plan_verify_local_time_limit
_plsql_conditional_compilation
_px_async_getgranule
_px_slaves_share_cursors
_seq_process_cache_const
_spr_use_hash_table
_sqlexec_progression_cost
_use_hidden_partitions
[ Read more ]

DBUA can ignore underscores with “keepHiddenParams”

The Database Upgrade Assistant (DBUA) is the graphical tool to upgrade Oracle databases. And the DBUA removes underscore parameters by default from the SPFILE when upgrading a database. If you don’t want this, there’s a way to tell it how DBUA can ignore underscores with “keepHiddenParams”.

DBUA can ignore underscores with “keepHiddenParams”

The DBUA by default will remove all underscores and events before actually doing an upgrade. This is expected behaviour as we believe that underscores or events were meant to treat misbehavior of the database just in a specific release only. And in our experience a nice collection … [ Read more ]