Table Internals: Stores, Compression, Partitioning & MVCC

What is a memory merge in SAP HANA, and what risk does it carry?

What SQL statement performs a forced merge in SAP HANA, and what makes it different from a hard merge?

In which cases does SAP recommend a CPBTREE index over a BTREE index for a row-store table?

What are merge tokens in SAP HANA, and what is the default number of tokens per table?

How do you add a partition to an existing partitioned SAP HANA table, and which partition types do NOT allow adding partitions?

When can hash partitioning use partition pruning in SAP HANA, and when can't it?

What SQL statement performs a hard merge in SAP HANA, and how does it behave with respect to the decision and token mechanisms?

Which SQL statement creates an SAP HANA table placement rule, and what is unusual about its assignment operator?

What is heterogeneous partitioning in SAP HANA?

What is dynamic range partitioning in SAP HANA, and what column types can it use?

What is an inverted hash index in SAP HANA and when should it be used?

Which SAP HANA column-store indexes are persisted to disk, and which are recreated at load time?

Which multilevel partitioning type is the most popular in SAP HANA, and why?

How does SAP HANA keep a column-store table available for reads and writes during a delta merge?

Which SAP HANA terminology is replacing 'master' and 'slave', and why?

How is a system-versioned temporal table physically structured in SAP HANA?

When is binary export/import between two SAP HANA systems a concern regarding endianness?

Which monitoring view holds the history of delta merge operations in SAP HANA, and how do you filter it for real table merges?

Which monitoring views show the in-memory load status of an SAP HANA column-store table, and what values indicate it?

Which column in the TABLES catalog view shows whether optimized compression is enabled for a column-store table?

Name the four multilevel partitioning specifications available in SAP HANA.

In what order are row-store and column-store tables loaded into memory when an SAP HANA instance starts?

Which parameter controls how often SAP HANA checks the threshold for dynamic range partitioning, and what is its default?

What does data scrambling do in an SAP HANA CSV export, and can it be reversed?

Since which SAP HANA version is the column store the default table type for new tables?

What are the default MVCC version thresholds whose breach SAP HANA warns about in the index server trace?

What is a smart merge in SAP HANA and which kind of application typically uses it?

How does a transactional savepoint in SAP HANA differ from the savepoint that writes memory to persistence?

What do the SAP HANA table-placement-rule properties MIN_ROWS_FOR_PARTITIONING, INITIAL_PARTITIONS, and REPARTITIONING_THRESHOLD control?

Why does a column-store table have a delta store in addition to its main store?

What are the two restrictions on dropping partitions in SAP HANA?

How do you change and how do you remove the classification attributes of an SAP HANA table?

What forms must range-partition conditions take in SAP HANA, and what is forbidden?

What is the fifth, internally managed kind of temporary table in SAP HANA?

How does SAP HANA's row-store MVCC implementation differ from the classic 'modify-in-place, before-image-aside' approach used by some databases?

What are the impacts of repartitioning a large SAP HANA table?

What are the three types of temporal table in SAP HANA, plus the combination type?

What three attributes does SAP HANA table classification add to a table, and which store does it apply to?

What are the internal hidden columns $rowid$, $trex_udiv$, and $trexexternalkey$ in an SAP HANA column-store table?

How does round-robin partitioning distribute rows in SAP HANA, and what is its key restriction?

How is the automatic table consistency check configured in SAP HANA, and where are its results stored?

What SQL statements enable or disable automatic delta merge for a single SAP HANA table?

What SQL statement moves a partition (or partition group) to another node in a distributed SAP HANA system?

What location keywords can be specified in the LOCATION property of an SAP HANA table placement rule?

Name the single-level partitioning specifications available in SAP HANA.

What is lazy loading of column-store tables in SAP HANA?

What data type and properties do columns automatically added to an SAP HANA flexible schema table receive?

What naming rule applies to a local temporary table in SAP HANA, and what is its lifetime?

Where are the results of manual SAP HANA consistency checks written?

What two isolation levels does SAP HANA support, and which is the default?

What SQL statement permanently disables or re-enables persistent storage of a table's delta merges in SAP HANA?

How does a no-logging table behave in SAP HANA regarding visibility, logging, and a restart?

What is the default index type for an SAP HANA column-store table, and how does an inverted value index work?

What two data formats does SAP HANA export/import support, and what are their store restrictions?

Which configuration parameter steers the SAP HANA automerge decision, and in which indexserver.ini section is it found?

What is the critical phase of an SAP HANA savepoint, and what is the recommended limit on its duration?

How do you mark an SAP HANA column-store table (or specific columns) to be preloaded into memory at startup?

How does a no-logging retention table differ from a plain no-logging table in SAP HANA?

How is MVCC realized in the SAP HANA column store?

What is a flexible schema table in SAP HANA, and how are new columns added?

Why can't the history table of an SAP HANA system-versioned table have a primary key constraint?

What range of page sizes does the SAP HANA persistence layer use for storing table data?

In a CALL to CHECK_TABLE_CONSISTENCY in SAP HANA, what does the keyword CHECK as first parameter mean, and how do you exclude specific checks or tables?

What is the role of the SAP HANA mergedog process?

What are SAP's rules of thumb for when to partition a table and how large each partition should be?

How do you turn a partitioned SAP HANA table back into a nonpartitioned one?

Why are primary keys not allowed with round-robin partitioning in SAP HANA?

What relationship must hold between a hash partitioning key and the primary key in SAP HANA?

What is a CPBTREE index in SAP HANA, and when is it the default?

What is a bitemporal table in SAP HANA?

Which monitoring views provide SAP HANA MVCC statistics, such as version memory and the table with the most open versions?

What is dangerous about the SAP HANA DROP PARTITION statement?

How does an SAP HANA application time-period table differ from a system-versioned table?

What SQL clause performs a time-travel query on an SAP HANA system-versioned table, and against which table is it run?

What does the SAP HANA IMPORT SCAN statement do?

Which two indexserver.ini parameters control startup loading of column-store tables in SAP HANA, and what are their defaults?

Why does SAP recommend against creating an OTHERS partition for a range-partitioned table?

What is the SAP HANA table unload priority scale, and what is the default?

What is an inverted individual index in SAP HANA, and what is its trade-off?

Which limitation makes partitioning mandatory rather than merely beneficial for an SAP HANA column-store table?

What is the default maximum number of partitions created by rule-based repartitioning in SAP HANA, and how is it changed?

What is the main advantage of multilevel partitioning over single-level partitioning in SAP HANA?

What is a savepoint in SAP HANA, and which parameter controls the automatic savepoint interval (and its default)?

How does dictionary compression work in the SAP HANA column store, and how many distinct values can one column hold?

How are SAP HANA table placement rules actually applied to a table after they are defined?

Which parameter sets the memory-usage threshold at which SAP HANA may drop no-logging retention tables, and what value disables the mechanism?

What is the SAP HANA DUMMY table and what is it used for?

Which catalog view column tells you whether an SAP HANA table is row-store or column-store?

Why does SAP HANA still need indexes despite being an in-memory database?

In SAP HANA multilevel partitioning, what is a partition group and where must its partitions reside?

What is a critical merge in SAP HANA and how is it steered?

How are full-text indexes created in SAP HANA for text vs. other column types?

For which table store type is partitioning available in SAP HANA?

What is the difference between a temporal table and a temporary table in SAP HANA?

How does SAP HANA clean up obsolete MVCC versions in the row store?

Which two stored procedures run consistency checks in SAP HANA, and what does each check?

Beyond dictionary compression, which advanced (optimized) compression techniques does the SAP HANA column store apply?

What are the easiest ways to find whether an SAP HANA table is partitioned and to read its partition specification?

Which SQL statements manually load or unload an SAP HANA column-store table or partition?

What characterizes a global temporary table in SAP HANA with respect to data visibility and persistence?

How do you make an SAP HANA EXPORT produce a compressed archive instead of a directory tree?

What happens in SAP HANA when an inserted row's value matches no defined range partition and there is no OTHERS partition?

Which SAP HANA EXPORT option exports only an object's metadata without its data, and which files are produced?

What happens by default if you IMPORT an object that already exists in SAP HANA, and how do you force a replace or filter by type?

What problem does multiversion concurrency control (MVCC) solve in SAP HANA, and what does it never do to readers?

How many index types does SAP HANA have, and how are they split between the stores?

What are the DML restrictions (DELETE, TRUNCATE, UPDATE/UPSERT/REPLACE) imposed by table store type on SAP HANA temporary tables?