Merge pull request #123149 from michae2/backport-staging-v23.1.20-122990

staging-23.1.20: stats: more conservative lower bound for downward-trending forecasts (#123149)

docs/generated/settings/settings-for-tenants.txt

@@ -273,6 +273,9 @@ sql.stats.cleanup.recurrence	string	@hourly	cron-tab recurrence for SQL Stats cl
 sql.stats.flush.enabled	boolean	true	if set, SQL execution statistics are periodically flushed to disk
 sql.stats.flush.interval	duration	10m0s	the interval at which SQL execution statistics are flushed to disk, this value must be less than or equal to 1 hour
 sql.stats.forecasts.enabled	boolean	true	when true, enables generation of statistics forecasts by default for all tables
+sql.stats.forecasts.max_decrease	float	0	the most a prediction is allowed to decrease, expressed as the minimum ratio of the prediction to the lowest prior observation
+sql.stats.forecasts.min_goodness_of_fit	float	0.95	the minimum R² (goodness of fit) measurement required from all predictive models to use a forecast
+sql.stats.forecasts.min_observations	integer	3	the mimimum number of observed statistics required to produce a statistics forecast
 sql.stats.histogram_buckets.count	integer	200	maximum number of histogram buckets to build during table statistics collection
 sql.stats.histogram_collection.enabled	boolean	true	histogram collection mode
 sql.stats.histogram_samples.count	integer	10000	number of rows sampled for histogram construction during table statistics collection

docs/generated/settings/settings.html

@@ -225,6 +225,9 @@
 <tr><td><div id="setting-sql-stats-flush-enabled" class="anchored"><code>sql.stats.flush.enabled</code></div></td><td>boolean</td><td><code>true</code></td><td>if set, SQL execution statistics are periodically flushed to disk</td></tr>
 <tr><td><div id="setting-sql-stats-flush-interval" class="anchored"><code>sql.stats.flush.interval</code></div></td><td>duration</td><td><code>10m0s</code></td><td>the interval at which SQL execution statistics are flushed to disk, this value must be less than or equal to 1 hour</td></tr>
 <tr><td><div id="setting-sql-stats-forecasts-enabled" class="anchored"><code>sql.stats.forecasts.enabled</code></div></td><td>boolean</td><td><code>true</code></td><td>when true, enables generation of statistics forecasts by default for all tables</td></tr>
+<tr><td><div id="setting-sql-stats-forecasts-max-decrease" class="anchored"><code>sql.stats.forecasts.max_decrease</code></div></td><td>float</td><td><code>0</code></td><td>the most a prediction is allowed to decrease, expressed as the minimum ratio of the prediction to the lowest prior observation</td></tr>
+<tr><td><div id="setting-sql-stats-forecasts-min-goodness-of-fit" class="anchored"><code>sql.stats.forecasts.min_goodness_of_fit</code></div></td><td>float</td><td><code>0.95</code></td><td>the minimum R² (goodness of fit) measurement required from all predictive models to use a forecast</td></tr>
+<tr><td><div id="setting-sql-stats-forecasts-min-observations" class="anchored"><code>sql.stats.forecasts.min_observations</code></div></td><td>integer</td><td><code>3</code></td><td>the mimimum number of observed statistics required to produce a statistics forecast</td></tr>
 <tr><td><div id="setting-sql-stats-histogram-buckets-count" class="anchored"><code>sql.stats.histogram_buckets.count</code></div></td><td>integer</td><td><code>200</code></td><td>maximum number of histogram buckets to build during table statistics collection</td></tr>
 <tr><td><div id="setting-sql-stats-histogram-collection-enabled" class="anchored"><code>sql.stats.histogram_collection.enabled</code></div></td><td>boolean</td><td><code>true</code></td><td>histogram collection mode</td></tr>
 <tr><td><div id="setting-sql-stats-histogram-samples-count" class="anchored"><code>sql.stats.histogram_samples.count</code></div></td><td>integer</td><td><code>10000</code></td><td>number of rows sampled for histogram construction during table statistics collection</td></tr>