Update performance-monitoring.md

Author: neSpecc

docs/performance-monitoring.md

@@ -6,26 +6,28 @@
 | Field | Type | Description |
 |-------|------|-------------|
 | id | string | Unique identifier of the transaction |
-| type | string | Type of transaction sampling ('default' or 'critical'). See [Sampling](#sampling) for details |
+| severity | string | Type of transaction sampling ('default' or 'critical'). See [Sampling](#sampling) for details |
 | name | string | Name of the transaction |
 | startTime | number | Timestamp when transaction started |
 | endTime | number | Timestamp when transaction ended |
 | duration | number | Total duration of transaction in milliseconds |
 | finishStatus | string | Status when transaction finished. 'success' (default) or 'failure'. See [Transaction Completion](#2-transaction-completion) |
 | spans | Span[] | Array of [spans](#span) associated with this transaction |
-| tags | object | Additional context data attached to transaction |
 
 ### AggregatedTransaction
 | Field | Type | Description |
 |-------|------|-------------|
-| id | string | Unique identifier of the transaction |
+| aggregationId | string | Identifier of the aggregation | 
 | name | string | Name of the transaction |
 | avgStartTime | number | Average timestamp when transaction started |
 | minStartTime | number | Minimum timestamp when transaction started |
 | maxEndTime | number | Maximum timestamp when transaction ended |
 | p50duration | number | 50th percentile (median) duration of transaction in milliseconds |
 | p95duration | number | 95th percentile duration of transaction in milliseconds |
 | maxDuration | number | Maximum duration of transaction in milliseconds |
+| count | number | how many transactions aggregated | 
+| aggregatedSpans | AggregatedSpan[] | List of spans in transactions | 
+
 
 ### Span
 | Field | Type | Description |
@@ -41,50 +43,57 @@ See [Transaction Aggregation](#transaction-aggregation) for details on how spans
 
 | Field | Type | Description |
 |-------|------|-------------|
-| id | string | Unique identifier of the span |
+| aggregationId | string | Unique identifier of the span aggregation |
 | name | string | Name of the span |
-| avgStartTime | number | Average timestamp when span started |
 | minStartTime | number | Minimum timestamp when span started |
 | maxEndTime | number | Maximum timestamp when span ended |
 | p50duration | number | 50th percentile (median) duration of span in milliseconds |
 | p95duration | number | 95th percentile duration of span in milliseconds |
 | maxDuration | number | Maximum duration of span in milliseconds |
 
-
 ## Transaction Lifecycle
 
 ### 1. Transaction Creation
+
 When creating a transaction, you can specify its type:
+
 - 'critical' - important transactions that are always sent to the server
 - 'default' - regular transactions that go through the [sampling process](#sampling)
 
 ### 2. Transaction Completion
+
 When completing a transaction:
+
 1. A finish status is specified (finishStatus):
    - 'success' (default) - successful completion
    - 'failure' - completion with error (such transactions are always sent to the server)
 
 2. The transaction duration is checked:
-   - If thresholdMs parameter is specified and the transaction duration is less than this value, the transaction is discarded
+   - If `thresholdMs` parameter is specified and the transaction duration is less than this value, the transaction is discarded
+   - Default `thresholdMs` is 20ms
+   - `finishStatus` "failure" has a priority over `thresholdMs`
    - Otherwise, the transaction goes through the [sampling process](#sampling)
 
-3. After successful sampling, the transaction is added to the list for sending
+3. After successful sampling, the transaction is added to the list for sending 
 
 ### 3. Sending Transactions
+
 - When the first transaction is added to the list, a timer starts
 - When the timer expires:
   1. All collected transactions are [aggregated](#transaction-aggregation)
   2. Aggregated data is sent to the server
   3. The transaction list is cleared
 
 ## Sampling
+
 - The probability of sending transactions is configured through the `performance.sampleRate` parameter (value from 0 to 1)
 - Only transactions of type 'default' with finish status 'success' are subject to sampling
 - Sampling process:
   1. A random number between 0 and 1 is generated for each transaction
   2. If the number is less than or equal to sampleRate, the transaction is sent
 
 ## Transaction Aggregation
+
 1. [Transactions](#transaction) are grouped by name (name field)
 2. For each group, statistical indicators are calculated:
    - minStartTime - earliest start time
@@ -94,8 +103,7 @@ When completing a transaction:
    - maxDuration - maximum duration
 
 3. Based on this data, [AggregatedTransaction](#aggregatedtransaction) objects are created
-
 4. For each aggregated transaction:
    - [Spans](#span) are grouped by name
-   - The same statistical indicators are calculated for each span group
+   - Their own statistical indicators (see [AggregatedSpan](#aggregatedspan)) are calculated for each span group
    - [AggregatedSpan](#aggregatedspan) objects are created