Documentation Source Text

  The default sorting procedure is to gather all information that will
  ultimately be output into a "record" and pass that complete record
  to the sorter.  But in some cases, for example if some of the output
  columns consists of large BLOB values, the size of the each record
  can be large, which means that the sorter has to either use more memory,
  and/or write more content to temporary storage.
  <p>
  When SQLITE_ENABLE_SORTER_PREFERENCES is enabled, the records passed to
  the sorter often contain only a [ROWID] value.  Such records are much
  smaller.  This means the sorter has much less "payload" to deal with and
  can run faster.  After sorting has occurred, the ROWID is used to look up 
  the output column values in the original table.  That requires another
  search into the table, and could potentially result in a slowdown.  Or,
  it might be a performance win, depending on how large the values are.
  <p>
  Even when the SQLITE_ENABLE_SORTER_PREFERENCES compile-time option is on,
  sorter references are still disabled by default.  To use sorter references,
  the application must set a sorter reference size threshold using the
  [sqlite3_config]([SQLITE_CONFIG_SORTERREF_SIZE]) interface at start-time.
  <p>
  Because the SQLite developers do not know whether the 
  SQLITE_ENABLE_SORTER_PERFERENCES option will help or hurt performance,
  it is disabled by default at this time (2018-05-04).  It might be enabled
  by default in some future release, depending on what is learned about its
  inpact on performance.
}

COMPILE_OPTION {SQLITE_ENABLE_STMT_SCANSTATUS} {
  This option enables the [sqlite3_stmt_scanstatus()] interface.  The
  [sqlite3_stmt_scanstatus()] interface is normally omitted from the build
  because it imposes a small performance penalty, even on statements that
  do not use the feature.

  The default sorting procedure is to gather all information that will
  ultimately be output into a "record" and pass that complete record
  to the sorter.  But in some cases, for example if some of the output
  columns consists of large BLOB values, the size of the each record
  can be large, which means that the sorter has to either use more memory,
  and/or write more content to temporary storage.
  <p>
  When SQLITE_ENABLE_SORTER_REFERENCES is enabled, the records passed to
  the sorter often contain only a [ROWID] value.  Such records are much
  smaller.  This means the sorter has much less "payload" to deal with and
  can run faster.  After sorting has occurred, the ROWID is used to look up 
  the output column values in the original table.  That requires another
  search into the table, and could potentially result in a slowdown.  Or,
  it might be a performance win, depending on how large the values are.
  <p>
  Even when the SQLITE_ENABLE_SORTER_REFERENCES compile-time option is on,
  sorter references are still disabled by default.  To use sorter references,
  the application must set a sorter reference size threshold using the
  [sqlite3_config]([SQLITE_CONFIG_SORTERREF_SIZE]) interface at start-time.
  <p>
  Because the SQLite developers do not know whether the 
  SQLITE_ENABLE_SORTER_REFERENCES option will help or hurt performance,
  it is disabled by default at this time (2018-05-04).  It might be enabled
  by default in some future release, depending on what is learned about its
  impact on performance.
}

COMPILE_OPTION {SQLITE_ENABLE_STMT_SCANSTATUS} {
  This option enables the [sqlite3_stmt_scanstatus()] interface.  The
  [sqlite3_stmt_scanstatus()] interface is normally omitted from the build
  because it imposes a small performance penalty, even on statements that
  do not use the feature.